WASHINGTON — Six Baltimore police officers will face no federal charges in the death of Freddie Gray, the 25-year-old black man who died of a severe spinal cord injury while in custody, the Justice Department announced on Tuesday.

“After an extensive review of this tragic event, conducted by career prosecutors and investigators, the Justice Department concluded that the evidence is insufficient,” the department said in a statement, adding that it was unable to prove the officers “willfully violated Gray’s civil rights.”

The closure of the criminal civil rights investigation into Mr. Gray’s death, which prompted unrest in Baltimore, a predominantly black city, and a federal examination of its police department’s practices, means that no officers will be held criminally responsible in his death.

Mr. Gray was arrested in April 2015 and charged with illegal possession of a switchblade after running from officers. Following his arrest, he rode in a police van — shackled but unsecured by a seatbelt, as required by police department regulations — and was found unresponsive. He died the following week.