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Maryland called in the national guard and declared a state of emergency after riots, arson and looting erupted in Baltimore on Monday night following the funeral of Freddie Gray.

Maryland Gov. Larry Hogan said he spoke to President Barack Obama and signed the order declaring a state of emergency "less than 30 seconds" after Mayor Stephanie Rawlings-Blake called to request it.

"Quite frankly we're glad she finally did," Hogan added.

Fifteen police officers were injured by flying debris, according to Col. Darryl DeSousa, the Baltimore police department's chief of patrol. He reported at least 27 arrests but said many more were expected after police review video of the violence and vandalism which wracked the city.

Maryland State Police, backed by the Maryland National Guard, will be the lead agency in the struggle to bring order to the city wracked with violence.

State police superintendent Col. William Palozzi said he was asking for the deployment of 500 law enforcement officers from throughout Maryland, up to 5,000 officers from nearby states to assist his force, and up to 5,000 Guardsmen in securing Baltimore's streets.

Baltimore Police Commissioner Anthony Batts said his department had been overwhelmed by the number of looters on Monday night.

"They just outnumbered us and outflanked us," Batts said. "We needed to have more resources out there."

Batts said the plan was for police to clear areas of demonstrators and for the National Guard to secure the area as police moved on to clear more territory.

Tensions have been mounting in Baltimore for a week following Gray's death in police custody. THey erupted on Monday night following his funeral. A police car and van were torched and several storefront windows were broken. A CVS pharmacy was looted then set ablaze, while the mall where the demonstrations began also saw looting and vandalism throughout the night.

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"This is not protesting, this is not your first amendment rights," he said. "This is just criminal activity."

Another van was set on fire and protesters forced firefighters to retreat from the scene, leaving the vehicle to burn, while Baltimore police later tweeted that demonstrators cut a fire hose to prevent firefighters from putting out a blaze.

We are deploying officers with the fire department to ensure fire fighting operations are not disrupted by people w/ no regard for life. -Baltimore Police (@BaltimorePolice) April 28, 2015

Batts — who described most of the crowds as "Baltimore youthful residents" who thought it was "cute to throw cinderblocks at the police — praised the actions of one embarrassed mom who grabbed her hood-wearing son and started "slapping his head."

"I wish I had more mothers out there like that," Batts said, urging parents to "take control of your kids."

Billy Murphy, an attorney for Gray's family, said they were in shock watching the violence unfold.

"They don't want this movement nationally to be marred by violence," he said. "It makes no sense. "This isn't a white/black issue, this is an issue of how do we treat each other as human beings."

His firm posted a statement on Facebook saying "Freddie Gray's family is watching the looting and rioting and is upset, sad, angry. They are begging people to stop this."

The mayor called the violent looters "thugs," saying there was a difference between the peaceful protesters of days past and "the thugs who only want to incite violence and destroy our city."

"Too many people have spent generations building up this city for it to be destroyed by thugs, who in a very senseless way are trying to tear down what so many have fought for," Rawlings-Blake said. "Tearing down business, tearing down or destroying property. Things that we know will impact our community for years."

"It is idiotic to think that by destroying your city you're going you're going to make life better for anybody," she added. Rawlings-Blake said there would be a weeklong curfew — starting Tuesday — imposed from 10 p.m. until 5 a.m. Meanwhile, Baltimore City Schools announced there would be no classes held on April 28.

Newly-sworn-in Attorney General Loretta Lynch earlier briefed President Barack Obama on the unfolding events in the Charm City, according to the White House.

Lynch condemned the "senseless acts of violence" and promised to "bring the full resources of the Department of Justice to bear in protecting those under threat, investigating wrongdoing and securing an end to the violence," the White House said in a statement.

As the situation deteriorated, Baltimore cops took to Twitter.

"Several juveniles are part of these aggressive groups. WE ARE ASKING ALL PARENTS TO LOCATE THEIR CHILDREN AND BRING THEM HOME," read a tweet on the official Baltimore Police Twitter feed.

The Rev. Jamal Bryant, who earlier delivered a eulogy at Gray's funeral, said the violence was not what was needed "just hours out of the burial."

"I'm asking every young person to go home," Bryant told reporters.

The Baltimore Sun reported the initial gathering of violent protesters stemmed from a flier distributed on social media calling for a "purge" to take place at 3 p.m., starting at the Mondawmin Mall and ending downtown.

The meme is based on the movie "The Purge," which imagines what would happen if there were no laws, the according to the Sun.

Earlier, Baltimore police said several gangs, including the Black Guerilla Family, Bloods, and Crips formed a partnership to "take out" law enforcement officers. The police said in a press release they consider the gang rumblings a "credible threat," but offered no specifics. The threats were enough to spur the LAPD to order its officers to ride in pair rather than solo "out of an abundance of caution" for their officers.

Gray was arrested after a foot pursuit on April 12 and was seen on video yelling as he was hauled into a police van. After a stop to shackle his feet, Gray arrived at a police station house with his spinal column 80 percent severed. He died a week later. Officials have promised an exhaustive investigation, with results due on May 1.