Baltimore police have handed prosecutors the findings of an internal investigation into the death of a black man who suffered spinal injuries while in custody, officials said on Thursday, a day after protests spread to other cities.

Police have said there were no plans to make the findings public, but the report was turned over to Baltimore City's chief prosecutor a day earlier than expected, Baltimore Police Commissioner Anthony Batts told a news conference.

"I understand the frustration, I understand the sense of urgency," Batts said. "That is why we have finished it a day ahead of time."

Batts said the police investigation of the death of 25-year-old Freddie Gray on April 19 was not over.

"If new evidence is found, we will follow it,” he said.

Prosecutors have said they would conduct their own investigation before deciding whether to charge six police officers involved in Gray's arrest on April 12.

Gray's death has become the latest flashpoint in a nationwide debate about police use of lethal force and race relations. Protests spread to other major cities on Wednesday for the first time since Gray died, a reprise of demonstrations that broke out last year after police killings of unarmed black men in Ferguson, Missouri,New York and elsewhere.

More than 100 people were arrested in New York overnight on Wednesday as protesters fanned out across Manhattan after a rally, briefly disrupting traffic in places.

The Baltimore police commissioner made the announcement about the report after a curfew held for a second night and relative calm returned to the predominantly African-American city. Looting, arson and street clashes with police roiled Baltimore on Monday after Gray's funeral.

On Thursday morning, thousands of National Guard troops and police remained in place. But the police presence was noticeably lighter than Wednesday.

On the street corner in West Baltimore where a CVS pharmacy burned and the worst of the rioting took place, only a dozen city police officers in normal patrol uniforms were on the street.

Authorities say Gray was running from police and when caught, transported to a police station in a van with no seat restraint. He suffered a spinal injury and died in the hospital. A lawyer for Gray's family says his spine was 80 percent severed at the neck while in custody.

In Baltimore, the outrage has ratcheted up expectations that there would be a quick answer on the fate of the six police officers involved in Gray's arrest. The officers have been suspended, and the U.S. Justice Department is investigating the incident for possible civil rights violations.

"We are confident that our state's attorney is going to do what needs to be done," said State Senator Catherine Pugh, who has been a frequent presence on Baltimore's streets the last two nights.

Pugh said the office of Marilyn Mosby, the state's attorney for the city, had to be given time to complete the probe.

PROTESTS AND ARRESTS

New York City police said early on Thursday most of the arrests were for disorderly conduct. The demonstrations from Union Square to Times Square and elsewhere, recalled protests in December after a grand jury decided against charges in the case of Eric Garner, an unarmed black man who died after a police officer put him in a chokehold.

Smaller protests were held in Boston, Houston, Ferguson, Washington, D.C., and Seattle, and a handful of demonstrators were arrested in Denver on Wednesday.

During Thursday's press conference, Baltimore police also revised their timeline of events that unfolded before Gray received medical attention.

Officials said the van in which Gray was riding after his arrest made an additional, previously undisclosed stop en route to a police booking center. Officials said they only learned about the stop from a private video taken along the van's route.

It was not immediately clear why the van stopped, and no further information was immediately available.

The Washington Post reported on Wednesday night that a prisoner who was in the same van as Gray, but who could not see him, heard him banging against the walls and believed he was intentionally trying to injure himself. The newspaper cited a document written by a police investigator.

Police have arrested close to 270 people since Monday's violence, 18 of them on Wednesday. Police said more than 100 people had been released without being charged because officials could not keep up with the paperwork, but he said charges would be brought later.

The unrest in Baltimore prompted national figures - from the new U.S. Attorney General Loretta Lynch to Democratic presidential candidate Hillary Clinton - to vow to work on improving law enforcement and criminal justice in minority communities.

The Baltimore neighborhood that saw the worst of Monday's violence was already filled with burned-out buildings and vacant lots that had not been rebuilt since the 1968 riots that followed the assassination of civil rights leader Martin Luther King Jr.