(CNN) Venezuela's self-declared interim president and opposition leader, Juan Guaido, is set to meet US Vice President Mike Pence in the Colombian capital Bogota Monday, following a weekend of deadly violence at the Venezuelan border.

Fresh violence erupted after the Venezuelan military blocked food and supplies from crossing the border from Colombia. The Colombian foreign minister said 285 people were hurt, and 37 hospitalized, after the Venezuelan National Guard fired tear gas and rubber bullets at protesters near the Colombian border Saturday.

Guaido, who is battling President Nicolas Maduro for control of the country, had called for other nations to send aid to Venezuela in response to worsening food and medicine shortages.

National Assembly Representative and Guaido supporter Adriana Pichardo told CNN that at least five people were also killed in clashes with Venezuelan security forces.

CNN cannot independently confirm the number of fatalities, but Michelle Bachelet, the UN high commissioner for human rights, said there were four deaths and 300 injuries Friday and Saturday.

Sunday was quieter. Small clashes broke out again at a town near the border with Colombia. CNN's team in Ureña, Venezuela, saw dozens of people throwing rocks toward Venezuela's National Guard, who fired back with rubber bullets. There was no report on injuries.

Maduro put out a defiant message Sunday.

"The people are united in the streets, mobilized and alert in every corner of the country," he said on Twitter. "I call on men and women of goodwill, not to lower their guard and to stay in the fight to preserve Venezuela's peace. Long live the Rebel homeland!"

El pueblo está unido en las calles, movilizado y alerta en todos los rincones del país. Llamo a los hombres y mujeres de buena voluntad, a no bajar la guardia y a mantenerse en pie de lucha para preservar la Paz de Venezuela. ¡Viva la Patria Rebelde! pic.twitter.com/5e4BxT6okx — Nicolás Maduro (@NicolasMaduro) February 24, 2019

When he arrived in Bogota, Guaido said, "Yesterday we saw an unprecedented crime with the burning of humanitarian aid that generously arrived at the Colombian collection point and which was then handed over to Venezuelan volunteers, who are again insisting that it's necessary to save lives. Venezuela today is again in crisis and it could have been alleviated yesterday."

Guaido declared that Saturday was the deadline to move the food and other supplies across the border.

But Maduro vowed to block the supplies, denying that a humanitarian crisis exists in Venezuela and suggesting that aid efforts are part of a US plot to orchestrate a coup.

Trucks torched

Bogota on Saturday night said all border crossings between Colombia and Venezuela would be closed Sunday and Monday so that authorities could evaluate damage to infrastructure it said had been caused by the Maduro government.

Venezuelan Communications Minister Jorge Rodriguez said Sunday -- after security forces had fired tear gas and rubber bullets at protesters -- that the country's security forces had protected the border in "exemplary" fashion.

But Bachelet, the UN official, said the violence was excessive.

"People have been shot and killed, others have reportedly received wounds from which they will never completely recover, including losing eyes," she said in a statement. "These are disgraceful scenes. The Venezuelan government must stop its forces from using excessive force against unarmed protesters and ordinary citizens."

The governor of Roraima, the Brazilian state bordering Venezuela, declared a state of medical emergency on Sunday, according to a press release from the Roraima Ministry of Health.

A Venezuelan Bolivarian National Guard officer throws a teargas grenade towards demonstrator in Urena Saturday.

Governor Antonio Denarium is quoted in the release saying the state's largest hospital, in the capital Boa Vista, is "at the brink of collapse" following the influx of victims injured in clashes across the border in Venezuela. As of now, 20 patients are being treated in Roraima hospitals, according to the release.

Trucks carrying supplies were blocked at most spots Saturday. Humanitarian aid moved through the Brazilian-Venezuelan border in Pacaraima, according to Maria Teresa Belandria, Venezuela's opposition-appointed ambassador to Brazil.

Witnesses said two trucks were set ablaze while attempting to cross into Venezuela from Colombia.

CNN cannot independently confirm the incident or the circumstances of how the two trucks were set on fire.

Rodriguez accused Guaido supporters of burning the trucks. While a CNN team saw incendiary devices from police on the Venezuelan side of the border ignite the trucks, the network's journalists are unsure if the trucks were burned on purpose.

Venezuelan soldiers faced off against protesters who were demanding to cross the border at Ureña to go work in Colombia, according to a CNN crew that witnessed the scene at the Tienditas Bridge.

In a sign that Maduro's grip on the military -- control of which is seen as integral to forcing new elections -- could be waning, Colombia's customs agency said Sunday that 104 members of Venezuela's security forces have defected, entering Colombia.

Images of burning trucks 'sickening'

In a series of tweets Saturday, US Secretary of State Mike Pompeo condemned the actions of Maduro's government and said the US would "take action against those who oppose the peaceful restoration of democracy in Venezuela."

"We denounce Maduro's refusal to let humanitarian assistance reach #Venezuela. What kind of a sick tyrant stops food from getting to hungry people? The images of burning trucks filled with aid are sickening," Pompeo tweeted

We denounce Maduro's refusal to let humanitarian assistance reach #Venezuela. What kind of a sick tyrant stops food from getting to hungry people? The images of burning trucks filled with aid are sickening. pic.twitter.com/bJ1Qsxkgx8 — Secretary Pompeo (@SecPompeo) February 24, 2019

"While Interim President Juan Guaido builds distribution networks for humanitarian assistance, Maduro blocks its entry and sends armed criminal gangs to attack the innocent civilians accompanying the convoys," Pompeo said in a statement Saturday

US leaders weigh in

On Monday, Pence will travel to Colombia to address a meeting of the Lima Group -- made up of leaders mostly from Latin American countries. The White House said Pence would "voice the United States' unwavering support for interim President Juan Guaido and highlight the Venezuelan people's fight for democracy over dictatorship."

A White House official said Saturday that Pence will meet with Guaido on Monday in Bogota, during Pence's visit to Colombia.

Photos: In photos: Venezuela in crisis Supporters of Venezuelan opposition leader Juan Guaido wave a Venezuelan flag as they wait for him to make an appearance in the country's capital of Caracas on Monday, March 4. Hide Caption 1 of 47 Photos: In photos: Venezuela in crisis Guaido greets supporters upon arriving at a Caracas airport on March 4. He crossed the border to Colombia in late February before embarking on a South American tour, meeting the presidents of Colombia, Brazil, Paraguay and Ecuador, along with US Vice President Mike Pence. By doing so, Guaido ignored a travel ban imposed on him by the country's Supreme Court. Hide Caption 2 of 47 Photos: In photos: Venezuela in crisis Guaido shakes hands with Pence in Bogota, Colombia, on Monday, February 25. The room was filled with humanitarian aid destined for Venezuela. Guaido's wife, Fabiana Rosales, is pictured at left. Hide Caption 3 of 47 Photos: In photos: Venezuela in crisis Demonstrators clash with Venezuelan soldiers at the Simon Bolivar International Bridge in Cucuta, Colombia, on Saturday, February 23. Hide Caption 4 of 47 Photos: In photos: Venezuela in crisis Supporters of President Maduro take part in a march in Caracas on February 23. Hide Caption 5 of 47 Photos: In photos: Venezuela in crisis Guaido supporters take part in a march in Caracas on February 23. Venezuelan security forces fired tear gas and rubber bullets to disperse a crowd demanding to cross the Venezuela-Colombia border, which was ordered closed by Maduro. Hide Caption 6 of 47 Photos: In photos: Venezuela in crisis Demonstrators push a bus that was set on fire during clashes with the Venezuelan National Guard in Urena, Venezuela, on February 23. Hide Caption 7 of 47 Photos: In photos: Venezuela in crisis Maduro waves the national flag during a pro-government march in Caracas on February 23. During the rally at the Venezuelan capital, Maduro told supporters he is breaking all diplomatic relations with Colombia and is calling for its ambassadors and consuls to leave Venezuela. Maduro recently began a second term after a 2018 vote that his political opposition and many in the international community denounced as a sham. Hide Caption 8 of 47 Photos: In photos: Venezuela in crisis People attempt to salvage packages from a truck loaded with humanitarian aid after it was set ablaze on a bridge between Cucuta, Colombia, and Urena, Venezuela, on February 23. Hide Caption 9 of 47 Photos: In photos: Venezuela in crisis Venezuelan opposition supporters protested in Caracas on Tuesday, February 12, calling on Maduro to let humanitarian aid into the economically crippled country. Hide Caption 10 of 47 Photos: In photos: Venezuela in crisis Guaido addresses the crowd in Caracas on February 12. Hide Caption 11 of 47 Photos: In photos: Venezuela in crisis A man wearing a Venezuelan flag sits on a traffic light during the demonstration in Caracas on February 12. Hide Caption 12 of 47 Photos: In photos: Venezuela in crisis Guaido waves to supporters during the rally in Caracas on February 2. Hide Caption 13 of 47 Photos: In photos: Venezuela in crisis An anti-government protester wears glasses with a Venezuelan flag motif at the demonstration in Caracas on February 2. Hide Caption 14 of 47 Photos: In photos: Venezuela in crisis Protesters gather for the Caracas rally on February 2. Hide Caption 15 of 47 Photos: In photos: Venezuela in crisis Maduro supporters gather in Caracas on February 2. Hide Caption 16 of 47 Photos: In photos: Venezuela in crisis Opposition demonstrators protest against Maduro's government on Wednesday, January 30. Hide Caption 17 of 47 Photos: In photos: Venezuela in crisis In this handout photo released by the Miraflores Presidential Press Office, Maduro flashes a "V for victory" hand gesture after arriving at the Fort Tiuna military base in Caracas on January 30. Hide Caption 18 of 47 Photos: In photos: Venezuela in crisis Members of the National Police line up to guard the entrance of Venezuela's Central University in Caracas during an anti-government protest on January 30. Hide Caption 19 of 47 Photos: In photos: Venezuela in crisis Guaido speaks to reporters in Caracas on January 30. The United States and more than a dozen other countries have recognized Guaido as Venezuela's legitimate ruler. Hide Caption 20 of 47 Photos: In photos: Venezuela in crisis A Maduro mural is seen in the Petare slum of Caracas on Tuesday, January 29. Hide Caption 21 of 47 Photos: In photos: Venezuela in crisis Guaido listens to deputy Rafael Veloz during a session at the National Assembly in Caracas on January 29. The Assembly met to debate a legal framework for creating a transitional government and calling new elections. Simultaneously, Venezuela's attorney general asked the Supreme Court to freeze Guaido's assets and bar him from leaving the country. Hide Caption 22 of 47 Photos: In photos: Venezuela in crisis A view of the National Assembly building in Caracas on January 29. Hide Caption 23 of 47 Photos: In photos: Venezuela in crisis The president of Venezuela's Supreme Court, Maikel Moreno, speaks at a news conference in Caracas on January 29. Hide Caption 24 of 47 Photos: In photos: Venezuela in crisis A man pumps fuel at a gas station in Caracas on January 29. A day earlier, the United States announced sanctions against Venezuela's state oil company, Petroleos de Venezuela, S.A. Hide Caption 25 of 47 Photos: In photos: Venezuela in crisis Supporters of Venezuela's opposition hold up letters that read "Justice" at a rally to hear Guaido speak in Caracas on Saturday, January 26. Hide Caption 26 of 47 Photos: In photos: Venezuela in crisis Guaido speaks to reporters after attending Mass in Caracas on Sunday, January 27. Hide Caption 27 of 47 Photos: In photos: Venezuela in crisis Government supporters in Caracas hold a rally in support of Maduro on January 26. Hide Caption 28 of 47 Photos: In photos: Venezuela in crisis Maduro holds a news conference in Caracas on Friday, January 25. The Venezuelan strongman has accused Guaido and the United States of trying to orchestrate a coup against him. Hide Caption 29 of 47 Photos: In photos: Venezuela in crisis Portraits of former Venezuelan leaders Simon Bolivar and Hugo Chavez hover in the background as Venezuelan Defense Minister Vladimir Padrino Lopez, bottom left, addresses a news conference in Caracas on Thursday, January 24. Venezuela's top military officials swore their allegiance to Maduro after other nations recognized Guaido as head of state. Hide Caption 30 of 47 Photos: In photos: Venezuela in crisis A man wrapped in a Venezuelan flag raises his arms in front of security forces during anti-government protests in Caracas on Wednesday, January 23. Hide Caption 31 of 47 Photos: In photos: Venezuela in crisis Opposition supporters in Caracas protest Maduro on January 23. Hide Caption 32 of 47 Photos: In photos: Venezuela in crisis Opposition supporters react to tear gas as they take part in the Caracas rally on January 23. Sporadic clashes erupted, but Maduro's military response to the protests seemed more measured than in the past. Hide Caption 33 of 47 Photos: In photos: Venezuela in crisis Police secure an area in Caracas on January 23. Hide Caption 34 of 47 Photos: In photos: Venezuela in crisis A National Police officer fires rubber bullets in Caracas. Hide Caption 35 of 47 Photos: In photos: Venezuela in crisis People raise their hands to show solidarity with Guaido, who was declaring himself interim president on January 23. Hide Caption 36 of 47 Photos: In photos: Venezuela in crisis A wounded protester in Caracas on January 23. Hide Caption 37 of 47 Photos: In photos: Venezuela in crisis Security forces stand in a street full of stones after clashing with demonstrators in Caracas. Hide Caption 38 of 47 Photos: In photos: Venezuela in crisis Maduro, speaking to a crowd of supporters at the Miraflores Palace in Caracas, holds up a document that says his government is breaking off diplomatic ties with the United States. "We cannot accept the invasive policies of the empire, the United States, the policies of Donald Trump," he said to cheers from the crowd on January 23. "Venezuela is a land of liberators." Hide Caption 39 of 47 Photos: In photos: Venezuela in crisis A wounded protester shows his back as riot police clashed with opposition demonstrators in Caracas on January 23. Hide Caption 40 of 47 Photos: In photos: Venezuela in crisis A man walks by a bus that had been set on fire in Caracas. Hide Caption 41 of 47 Photos: In photos: Venezuela in crisis An opposition demonstrator runs with a tear-gas canister on January 23. Hide Caption 42 of 47 Photos: In photos: Venezuela in crisis Guaido greets a crowd in Caracas on January 23. Hide Caption 43 of 47 Photos: In photos: Venezuela in crisis Protesters set up barricades to block a road in Caracas. Hide Caption 44 of 47 Photos: In photos: Venezuela in crisis A National Police officer fires tear gas at demonstrators in Caracas while another shoots the scene with a cell phone. Hide Caption 45 of 47 Photos: In photos: Venezuela in crisis Demonstrators in Caracas protest Maduro's government. Hide Caption 46 of 47 Photos: In photos: Venezuela in crisis Venezuelan banknotes were thrown on the ground during the Maduro protests on January 23. Hide Caption 47 of 47

Republican Florida Sen. Marco Rubio said on Twitter that the Maduro regime had "overplayed its hand" through its actions Saturday, making it easier for the international community to isolate it and harder for regime allies to continue supporting it.

"Today #MaduroRegime killed unarmed citizens of their own country to keep food & medicine from entering. They celebrated murder & burning of trucks carrying aid as a victory. The world & those inside #Venezuela will reflect on what happened today & it will give rise to action," he tweeted

Senator and Democratic presidential candidate Bernie Sanders tweeted : "The people of Venezuela are enduring a serious humanitarian crisis."

Maduro cuts relations with Bogota

Maduro declared Venezuela's borders with Brazil and Colombia closed, citing threats to security and sovereignty.

On Saturday he told supporters he was breaking all diplomatic relations with Colombia and calling for its ambassadors and consuls to leave Venezuela.

Colombian Foreign Minister Carlos Holmes Trujillo said all the diplomats were ordered to leave immediately for their safety. Four Colombian consuls have returned from Venezuela, Colombian immigration officials said Sunday.

Maduro also threatened the United States: "If the empire dares to attack, they will be received by the strength of the Venezuelan armed forces."

Maduro challenged Guaido on Saturday to call for new elections, but on Sunday Guaido's spokesman, Edward Rodriguez, told CNN they're not going to do that because "we set the agenda."

Guaido has always said that he will call elections 30 days after "the usurper had left power" -- and that hasn't happened yet, Rodriguez said.