Baltimore’s top police officials, mayor and prosecutor sought to calm a “community on edge” Monday while investigating how a man suffered a fatal spine injury while under arrest.

Six officers were suspended, but a week after Freddie Gray was pulled off the street and into a police van, authorities have no videos or other evidence explaining what happened to cause the “medical emergency” Gray suffered while being taken to the local police station April 12, Deputy Commissioner Jerry Rodriguez said.

Autopsy results returned Monday show that Gray “did suffer a significant spinal injury that led to his death,” Rodriguez said. “What we don’t know is how he suffered that injury.”

Something must have happened between the time Gray was videotaped by a bystander being dragged into the van and when he arrived at the station in deep distress, Rodriguez said.

“When Mr. Gray was put in that van, he could talk, he was upset. And he was taken out of that van, he could not talk and he could not breathe,” he said.

Police Commissioner Police Commissioner Anthony Batts said he is ordering that police review and rewrite “effective immediately” its policies on moving prisoners and providing them with medical attention.

“We are a community on edge right now. We hear, I hear, the outrage. I hear the concern and I hear the fear,” Batts said, asking for calm.

Mayor Stephanie Rawlings-Blake said she was “angry that we are here again” after trying to overcome decades of distrust between police and citizens in Baltimore’s inner city.

All six officers involved in the Gray case have been suspended, said Rodriguez, who is in charge of the department’s professional standards and accountability.

Officer Garrett Miller’s official request for a criminal charge against Gray, a 25-year-old black man who was 5-feet-8-inches tall and weighed 145 pounds, said that he had been arrested “without force or incident.” Miller sought to charge him with carrying a switchblade.

The document doesn’t provide any explanations for the injuries that would lead to Gray’s death a week later. Miller wrote only that while being taken to the station, “the defendant suffered a medical emergency and was immediately transported to Shock Trauma via medic.”

Another 30 minutes passed before police finally called an ambulance to pick Gray up at the station. He arrived at the hospital in critical condition and died on Sunday after a weeklong coma.

Activists protesting excessive use of force and even Baltimore city officials say they have more questions than answers. About 50 people marched from City Hall to police headquarters Monday.

“This is just one of the most egregious cases I’ve ever seen,” said Colleen Davidson of the Baltimore People’s Power Assembly, which she said organized the rally at the request of Gray’s family. “We felt the need to be out here and make it known that we will not stand and watch things like this happen.”