One officer faces a second-degree murder charge while the other officers face manslaughter or assault charges, among others.
Mosby says the officers failed to get Gray medical help even though he requested it repeatedly after he was arrested April 12. She called his arrest illegal.
At some point while he was in custody, he suffered a mysterious spinal injury and died a week later.
The Baltimore police officers union says the six officers charged in the Freddie Gray case aren't responsible for his death.
Fraternal Order of Police Lodge 3 President Gene Ryan made the comment Friday in a letter to Mosby before she announced the charges. It was the union's strongest statement to date in the officers' defense.
"As tragic as this situation is, none of the officers involved are responsible for the death of Mr. Gray," Ryan wrote. "To the contrary, at all times, each of the officers diligently balanced their obligations to protect Mr. Gray and discharge their duties to protect the public."
Ryan asked Mosby in the letter to appoint a special independent prosecutor. But after announcing charges Friday, Mosby said she would not turn the case over to a special prosecutor.
The union contracts with an attorney, Michael Davey, who has said that five of the six officers gave voluntary statements on the day of Gray's arrest.
