'Active shooter' in Cleveland streams live killing of man

Cleveland police fear a man who shot and killed another man while livestreaming on Facebook may have fled the state.

Steve Stephens posted two videos on Facebook - one where he can be seen shooting an elderly man, identified as 74-year-old Robert Godwin Sr.

In the second, he rants about his motivations for the crime, saying he "just f***ing snapped".

"I just woke up on Friday and couldn't take it and now here I am, massacring motherf***ers," he said in the video.

He also claimed to have killed more than a dozen other people, but police say no other victims have been found.

Facebook later shut down Stephens' account, but the video of the slaying remained online for more than three hours after it was posted.

"This is a horrific crime and we do not allow this kind of content on Facebook," a company spokesperson said.

"We work hard to keep a safe environment on Facebook, and are in touch with law enforcement in emergencies when there are direct threats to physical safety."

Cleveland police said Stephens is armed and dangerous and shouldn't be approached.

"At this time, there are still NO known additional victims. We ask that the public remain aware and report any suspicious activity to police immediately," it said in a statement.

"Officers and agents continue to investigate leads as they come in."

It's feared he's since left Ohio and residents in Pennsylvania, New York, Indiana and Michigan are told to be on the alert.