Cleveland police issued an arrest warrant Monday for a gunman they said murdered a man in a crime he broadcast live on Facebook.
Officials in the Ohio city said suspect Steve Stephens, 37, shot his 74-year old victim Robert Godwin Sr at random on Easter Sunday, in cold blood.
"Suspect did broadcast the killing on Facebook Live and has claimed to have committed multiple other homicides which are still NOT verified," Cleveland police said in a statement.
"Suspect in this case is... armed and dangerous. If seen call 9-1-1. Do not approach."
Police said Stevens may be out of the midwestern state, and asked residents of Indiana, Michigan, New York and Pennsylvania to be on alert.
Stevens worked for Beech Brook, a behavioral health agency serving children through mental health services, foster care and adoption, at-risk youth programs and other services.
In his broadcast, Stevens displayed his Beech Brook badge. The facility did not immediately respond to requests for comment.
At a press conference late Sunday, authorities urged Stephens to turn himself in.
"Everyone is out there looking for Steve. We want this to end with as much peace as we can bring to this right now, and we want him to turn himself in," Cleveland Police Chief Calvin Williams told reporters, adding that local authorities were working with the FBI and regional law enforcement.
"We have all of our partners in on this, and we'll look until we find him."
Mayor Frank Jackson told reporters police were still trying to communicate with the suspect.
"We want to communicate to him that we know who he is, and that he will eventually be caught. And that we're saying to him that he need not do any more," said Jackson.
Stephens was at large after fleeing in a white Ford Fusion with temporary license plates, police said.
Some local media reported that he had boasted on Facebook of killing more than a dozen people in an Easter Day massacre, but authorities said there was no indication of a broader killing spree.