BALTIMORE (AP) - Baltimore's top prosecutor charged six police officers with felonies ranging from assault to murder in the death of Freddie Gray, triggering celebrations and a sense of relief in the tension-filled city. 

State's Attorney Marilyn Mosby said Friday that Gray's arrest was illegal and unjustified, and that his neck was broken because he was handcuffed, shackled and placed head-first into a police van, where his pleas for medical attention were repeatedly ignored as he bounced around inside the small metal box.

The swiftness of her announcement, less than a day after receiving the police department's criminal investigation and official autopsy results, took the city by surprise. So too did her detailed description, based in part on her office's independent investigation, of the evidence supporting probable cause to charge all six officers with felonies.

Gray's death came amid a national debate about the deaths of black men at the hands of police.

The police had no reason to stop or chase after Gray, Mosby said. They falsely accused him of having an illegal switchblade when in fact it was a legal pocketknife. The van driver and the other officers failed to strap him down with a seatbelt, a direct violation of department policy, and they ignored Gray's repeated pleas for medical attention, even rerouting the van to pick up another passenger.

Mosby did not say whether there was any indication the driver deliberately drove erratically, causing Gray's body to strike the van's interior. In 2005, a man died of a fractured spine after he was transported in a Baltimore police van in handcuffs and without a seat belt. At a civil trial, an attorney for his family successfully argued police had given him a “rough ride.”

The officers missed five opportunities to help an injured and falsely imprisoned detainee before he arrived at the police station no longer breathing, she said. Along the way, “Mr. Gray suffered a severe and critical neck injury as a result of being handcuffed, shackled by his feet and unrestrained inside of the BPD wagon,” she concluded.

Her announcement triggered celebrations across the same West Baltimore streets that were smoldering just four days earlier, when Gray's funeral led to riots and looting.

“We are satisfied with today's charges,” Gray's stepfather, Richard Shipley, told a news conference. “These charges are an important step in getting justice for Freddie.”