The refusal of authorities to provide more than a few sketchy details about the Freddie Gray investigation may be legally appropriate, but many people in Baltimore were finding it hard to be patient Thursday when police revealed nothing about the internal investigation they turned over to the state's attorney's office.

Nearly two weeks after Gray's death, the public still doesn't know much more than it did on Day One. The central question - what caused his fatal spinal cord injury - remains a mystery.

"The transparency is just not there," Rev Cortly Witherspoon said after Police Commissioner Anthony Batts refused to answer any questions Thursday.

Batts said his department's report was delivered a day ahead of time to State's Attorney Marilyn Mosby, and that from now on, any questions should go to her.

Mosby also declined to talk, issuing a statement Thursday asking "for the public to remain patient and peaceful and to trust the process of the justice system."

With rumors flying about how Gray's spine was "80 percent severed," as his family's lawyer Billy Murphy put it, police did release a new piece of information Thursday, but it served mostly to raise more questions about how truthful six suspended officers have been with investigators.

Baltimore's police Commissioner Anthony Batts said a nighttime curfew for the city will remain in effect through the weekend.

Batts did not say when the curfew would be lifted. He said authorities were expecting large marches this weekend.

The city has been on edge since the police-custody death of Freddie Gray, and the riots that erupted on the day of his funeral.

Among the hundreds marching in Baltimore in support of Freddie Gray Thursday was NBA star Carmelo Anthony, who moved to the city as a child.

"We're being heard. We've just got to be careful to do it the right way. We can't become violent ... we've got to be patient," said Anthony, the New York Knicks starter who was born in Brooklyn.

Police clashed with several hundred people gathered at City Hall in Philadelphia to protest Gray's death and raise concerns about police in their own city.

Chants of "No justice, no peace," and "Black lives matter" filled Dilworth Plaza late Thursday afternoon as news helicopters hovered overhead. Several dozen uniformed police officers stood guard while plainclothes officers patrolled nearby.

Some activists and elected officials are criticizing the New York Police Department's handling of protests over the Gray death.

The critics say the NYPD was overly aggressive and at times violent.

Police Commissioner William Bratton said 143 people were arrested Wednesday night during a rally and march.

Bratton said police would be "more assertive" than they were during December protests in the wake of the Eric Garner grand jury decision.