PHILADELPHIA (AP) - A 25-year-old man has been charged with committing four separate slayings over nine months, and the Philadelphia district attorney described him Friday as a contract killer who was paid thousands of dollars for his work.

Police accused Steven M. Williams of killings that occurred in September 2018 and in February, March and May of 2019.

Philadelphia District Attorney Larry Krasner called Williams an alleged contract killer in a news release announcing the charges.

Krasner said that when the victims were shot and killed, three were in or getting out of cars and the fourth was sitting on a front porch.

"His streak of wanton, violent crimes against our communities over the past two-plus years ends today," Krasner said.

Krasner said Williams is doing state prison time for unrelated crimes.

Online court records indicate Williams was denied bail.

A spokesman for the Defender Association of Philadelphia , which represents him, declined comment.

Williams is also accused of gun offenses and other allegations.

Police said Williams, of the 6900 block of Ogontz Avenue, was arrested Wednesday afternoon.