A call to unite those affected by President Donald Trump’s rhetoric on immigration and deportation policies drew a sea of people to downtown Los Angeles on Monday for a diverse May Day march and rally.

Dubbed Resist Los Angeles, the march was one of the largest May 1 events in the nation, with organizers saying 30,000 people gathered at MacArthur Park and marched 21/2 miles through closed streets to City Hall downtown.

Participants from a network of 100 labor and civic groups hoisted signs and banners, as well as a giant American flag, to speak in favor of workers’ rights and better wages, as well as against Trump’s proposed border wall, his hard stance on illegal immigration and his policies that temporarily ban refugees from some Middle Eastern countries.

• RELATED PHOTOS: May Day protesters march toward downtown LA Civic Center, where Trump supporters are waiting

Marvin Ortiz, a member of Progesso Legal Group, told the crowd through a megaphone that the march should be peaceful and should show the country that immigrants, legal or not, should be grateful to the United States for many opportunities. But it was important, he added, to speak for the voiceless.

“We respect this flag, this country,” Ortiz said to applause. “We respect this president. He’s our president. But we’re here to give voice to those who have none. Those who unfairly sit in detention centers, those who pick tomatoes, lettuce, in jobs no one else will do.”

Signs that read “Build bridges not walls” and “No more family separation” were lifted in the air as hundreds of people shouted “Si se puede! (Yes we can!),” a chant associated with the labor union formed by Cesar Chavez.

This year’s march drew members from the Los Angeles Black Workers Center, the Korean Resource Center, the Writer’s Guild of America, unions that represents nurses, clergy from several faiths and the LGBTQ community among many other groups that said Trump’s rhetoric seemed to affect them all.

“He brought us together,” said Ari Gutierrez, board president for the Latino Equality Alliance, an organization that serves the LGBT Latino community. “We have to work together to show solidarity.”

• MAP: See and print the full map of today’s May Day marches and rallies

Just before the march began, Tom Morello from the group Rage Against the Machine stood on a platform with his acoustic guitar and said he was a proud member of the local musician’s union before leading the crowd into “This Land Is Your Land.”

“This is a worker’s song! This is an immigrant’s song!” he said. “This is a reminder to you and anybody who would hold us down that this land is your land!”

Unlike past May Day marches, there was more urgency in the message behind this year’s gathering, some said.

Since Trump stepped into the White House in January, similar rallies in Los Angeles and in cities across the nation have been held by demonstrators on behalf of immigrants, women, science, climate change and to demand the president release his tax returns.

In his defense, about 50 Trump supporters also gathered in downtown Los Angeles outside the Federal Building and sang the National Anthem. One anti-Trump demonstrator was arrested for arson when he burned the American flag, but there were no other arrests, according to an LAPD spokeswoman.

Trump released a statement on Friday, proclaiming May Day as Loyalty Day.

“The United States stands as the world’s leader in upholding the ideals of freedom, equality, and justice,” he said in the proclamation. “On this day, we honor the United States of America and those who uphold its values, particularly those who have fought and continue to fight to defend the freedom it affords us.”

Monday’s march was organized by the May Day Coalition of Los Angeles led by the Coalition for Humane Immigrant Rights of Los Angeles and other groups.

Leaders from CHIRLA have said Trump’s policies toward undocumented immigrants have led to a surge in deportations.

Several groups staged smaller rallies in other parts of the city, including in Boyle Heights, with all of them converging on City Hall, which had not been done since the May Day march in 2006, to symbolize unity among the groups, organizers said.

At City Hall, Los Angeles Mayor Eric Garcetti spoke to the marchers in English and in Spanish, reassuring the crowd that as long as he is mayor, the Los Angeles Police Department will not assist the federal government in deportation efforts.

“Here in Los Angeles, we show love is stronger than hate,” he said. “It matters less who’s in the White House but who’s in this house.”

Some members of the United Teachers Los Angeles labor union also marched. They had requested that the Los Angeles Unified School District shut down for the day, to allow teachers and others to participate, but Superintendent Michelle King said it was best to keep schools open so that students can learn about civics in the classroom.

“This is not a moment,” said Cynthia Myart-Cruz of UTLA. “This is a movement.”

While May Day eventually became known as International Workers’ Day by socialists and communists around the world, in the U.S. the day has come to focus on immigration reform as well as fair wages.

Indeed, many people wore the familiar red shirts, but thousands of others said they marched because, this time, it seemed lives depended on it.

“I don’t protest for myself,” said Maria Lopez, 70, a retired Arcadia teacher. “I don’t vote for myself. I do what’s best for the entire country.”

Anna Cardenas, 53, of Rancho Cucamonga took a day off from work as a librarian at Western University of Health Sciences because she said it was important to support the Affordable Care Act, which allowed her developmentally disabled son medical coverage through Medi-Cal.

“I wouldn’t know what to do without it,” Cardenas said. “I march because I’m scared for my son.”

Staff writer Christopher Yee contributed to this report.