(Bloomberg) -- National Guard troops movedinto Baltimore after a black man’s death in policecustody set off riots, prompting officials to declare a state ofemergency, impose a curfew and close schools.

Maryland Governor Larry Hogan asked the National Guard into thecity as protesters attacked police with rocks and bricks and setcars and buildings on fire Monday. The violence erupted after thefuneral of Freddie Gray, 25, who died on April 19 after sufferingspinal-cord injuries while in police custody.

Fifteen officers were injured and 27 people were arrested, saidDarryl De Sousa of the Baltimorepolice department. The riotsfollow protests in other cities such as Ferguson, Missouri, whereblacks died in encounters with law enforcement.

“We are going to be out in massive force,” Major General LindaSingh, adjutant general of the state’s national guard, said in atelevised news conference. Hundreds of troops were on the groundinBaltimore early Tuesday, the Maryland National Guard said onits Facebook page.

T. Rowe Price Group Inc. saidits Baltimore headquarters on will stay closed Tuesdaybecause of the riots. Legg Mason Inc., also basedin Baltimore, is encouraging employees to work from home,spokeswoman Mary Athridge said by phone.

The violence began when high school students gathered at thecity’s Mondawmin Mall and began throwing concrete blocks and rocksat officers, Baltimore police Commissioner Anthony Battssaid. Television images showed looting at a check-cashing businessand the destruction of a police vehicle in the city, which is about65 kilometers (40 miles) northeast of Washington.

Gang Threat

Authorities had indications that gangs decided at a meeting onSunday they would attempt to kill officers after Gray’s funeral,Batts said.

“They said at the conclusion of Mr. Gray’s funeral today eachgroup was intending to kill and take out a police officer,” he toldreporters.

Gray’s sister, Fredericka Gray, condemned the rioting.

“I don’t agree with the violence that they’re doing to the city-- it’s too much,” she told reporters. “I don’t think that’s forFreddie. I think they’re doing violence for something else.”

Baltimore public schools are closed on Tuesday, the firstday of a citywide curfew that requires residents to remain homebetween 10 p.m. and 5 a.m. Baltimore Mayor StephanieRawlings- Blake said the restrictions would last for at least aweek, and that juveniles were already subject to a curfew.

Obama Briefed

Monday night’s Major League Baseball game between the ChicagoWhite Sox and Baltimore Orioles was postponed by theteam. Oriole Park at Camden Yards is about 2 miles from a CVS storethat was looted and then set ablaze. Police said rioters cut a hosethat was being used to fight the fire.

“Too many people have spent generations building up this cityfor it to be destroyed by thugs who in a very senseless way aretrying to tear down what so many have fought for,” Rawlings-Blakesaid.

President Barack Obama was briefed Monday on the situationin Baltimore by Attorney General Loretta Lynch, who saidthe Justice Department is poised to provide any needed assistanceto local authorities, according to a White House statement. Obamaalso spoke with Hogan and Rawlings-Blake about the city’s effortsto maintain order.

Police Tensions

The Justice Department has opened a preliminary civil- rightsinquiry into Gray’s death, as the Obama administration scrutinizeslaw-enforcement practices nationwide.

Last month, the Justice Department criticized the civil- rightsrecord of police in Ferguson after the fatal shooting of an unarmedblack teenager by an officer in the St. Louis suburb.

Michael Brown’s shooting on Aug. 9 and several other incidentsaround the U.S., including the death of an unarmed black man whowas placed in a chokehold by a white New York City police officer,sparked widespread protests.

Six Baltimore police officers have been suspended asauthorities investigate the circumstances of Gray’s arrest andwhether criminal charges are warranted.

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