DETROIT (AP) -- The mayor of Detroit is firing the city's police chief, a person familiar with the situation said Friday.

The person told the Associated Press that Mayor Dave Bing has told Police Chief James Barren that the chief is being relieved of his duties. The person talked with Barren on Friday, a day after a man arrested in the shooting of seven teenagers at a Detroit bus stop was released due to lack of evidence.

The person spoke to the AP on condition of anonymity because the person wasn't authorized to publicly discuss Barren's dismissal. The person did not know when it was to become official.

"There have been no changes or announcements regarding changes at the Detroit Police Department at this time," Bing spokeswoman Karen Dumas said Friday.

A telephone listing for a James Barren in Detroit was not working. Messages were left with the police department.

Assistant Chief Ronald Fleming told the Detroit Free Press that Barren told him Wayne County Sheriff Warren Evans would take over as chief starting Monday.

Evans did not immediately return a message from the AP. A voicemail box at a listing for Ronald Fleming in Detroit was full.

Word of Barren's firing came a day after an 18-year-old man arrested on suspicion of shooting the teens at the bus stop was released because Wayne County Prosecutor Kym Worthy determined there was a lack of evidence. Barren had said the man was identified as a suspect after investigators spoke with victims of Tuesday's shooting and another person with knowledge of the incident.

No other arrests have been made.

Interim Mayor Ken Cockrel Jr. promoted Barren from deputy chief to head of the police force in the nation's 11th-largest city in September. He succeeded Ella Bully-Cummings, who announced her retirement after the man who appointed her, former Mayor Kwame Kilpatrick, pleaded guilty to two felony obstruction charges in a sex-and-misconduct scandal.

Barren, who has a doctoral degree, said he wanted to raise officer morale.

Bing defeated Cockrel in a May 5 runoff to serve out the remainder of Kilpatrick's second term, which ends in December. He and five other candidates face off in an Aug. 5 primary, with the top two vote-getters advancing to the Nov. 3 general election.