PHILADELPHIA - Thousands of people gathered in Philadelphia and Pittsburgh on Saturday to protest the death in Minneapolis of George Floyd, but the peaceful demonstrations later turned violent with police cars set ablaze and protesters smashing store windows and journalists attacked.

Both cities implemented citywide curfews until Sunday morning, and Gov. Tom Wolf signed a disaster emergency declaration to assist cities. The declaration authorizes the adjutant general of the state National Guard and the Pennsylvania State Police Commissioner to activate personnel.

“Peaceful protests earlier were touching shows of our collective grief,” Philadelphia Mayor Jim Kenney said Saturday night, just as the city’s curfew hit. “But the anger being displayed this afternoon cannot and will not continue.”

In Pittsburgh, public safety officials said multiple officers were injured and three journalists were attacked or injured by protesters. The injuries weren’t serious, police said. Officials urged people to avoid downtown, where a police vehicle was torched earlier, as demonstrations continued into the evening.

Earlier Saturday, a crowd gathered at Philadelphia’s City Hall, kneeling for more than eight minutes in honor of Floyd, a black man who died after a white officer pressed a knee into his neck for several minutes. The protesters then marched through Center City to the Philadelphia Museum of Art.

At least 13 police officers were injured at several locations throughout Center City, Police Commissioner Danielle Outlaw said. A bike officer trying to stop a vehicle carrying people believed involved in a store theft was run over by the car and suffered a broken arm, police said.

There were also injuries to civilians, she said, but specific numbers have not yet been released. At least four police vehicles were set on fire.

Protesters broke windows and grabbed things from store shelves throughout Walnut and Chestnut streets, two major shopping areas downtown.

Protesters sprayed graffiti on a statue of former Philadelphia Mayor Frank Rizzo, tried to topple it and set a fire at its base. Rizzo, mayor from 1972 to 1980, was praised by supporters as tough on crime but accused by critics of discriminating against minorities. His 10-foot-tall (3-meter-tall) bronze statue outside the Municipal Services Building, across from City Hall, has been defaced before and is to be moved next year.

Outlaw said that at least nine separate fires were set in the city, to both police cars and structures. A Starbucks coffee kiosk, situated in the plaza in front of City Hall, was set afire.

As of 9 p.m. Saturday, 14 arrests were made, police said.

Kenney, a Democrat, signed an emergency executive order implementing a curfew Saturday night and Sunday night, both from 8 p.m. to 6 a.m. Only essential workers or those who need medical attention should be outdoors, according to the order.

In Pittsburgh, crowds marched downtown to protest Floyd’s death. Police reported that the crowd near the PPG Arena was mostly peaceful but a group “overtook and destroyed” a marked police vehicle.

Protesters later smashed a glass business front and were dispersed with gas, police said. Pittsburgh Public Safety later reported more business fronts broken out in the downtown area “and protests are entering businesses.”

Wendell Hissrich, the city’s public safety director, said there is “extensive” damage downtown. A curfew is in effect until 6 a.m. Sunday.

In Harrisburg, PennLive.com reports that several hundred people gathered Saturday on the steps of the state Capitol, many standing silently with raised fists. Some chanted “I can’t breathe” and carried signs such as “White Silence is Violence,” “Fight for Your Country” and “No Peace No Justice.”

Wolf’s declaration acknowledged the protests in Philadelphia, Pittsburgh and Harrisburg. The declaration and expanded activation of the Commonwealth Response Coordination Center allocates funds to the Pennsylvania Emergency Management Agency, which is authorized to direct emergency operations in Allegheny, Dauphin and Philadelphia counties.