"I found somebody I'm about to kill," the man said in the video, as he pulled his Ford Fusion to the side of a road in east Cleveland about 2 p.m. Sunday.
"I'm about to kill this guy right here. He's an old dude," the man said as he confronted Robert Godwin Sr., 74, who was walking on the sidewalk.
"Can you do me a favor?" the man asked Godwin before asking that he say the name of a woman. "She's the reason this is about to happen to you."
The shooter -- whom police suspect is Steve Stephens, 37 -- then asked Godwin's age before killing him. The interaction lasted less than a minute. The two men did not know each other, police said.
Stephens said in the live video that he has killed more than a dozen people, police said, though they have announced no other victims.
Authorities searched Sunday night across the Cleveland area for the suspect, who they said is African-American, 6-foot-1, bald and has a full beard. Police said he is driving a white Ford Fusion with the temporary Ohio plate E636360.
Facebook allows any user to live-stream video from their phones, a service started in 2010. As the live videos have gained in audience and prominence, some have questioned how the company should best control for potentially horrific scenes. The video of Sunday's homicide was viewable on Facebook for about three hours before it was removed and Stephens' profile was deactivated.
The video is likely to reignite a debate about the haunting reach of grisly violence in the Internet age, and follows shocking beatings and killings shared in real time on a global stage.
Three men were shot last year in Norfolk, Virginia, while one was broadcasting live on Facebook from inside a car. And in 2015, a shooter killed a TV journalist and her cameraman during a live-TV broadcast before posting his own video of the killing on Facebook.
In January, four people in Chicago were accused of attacking an 18-year-old disabled man while broadcasting the assault on Facebook Live. They have since pleaded not guilty.
Other live platforms have been used to broadcast haunting videos. An Ohio woman was accused of broadcasting her friend's rapist on Twitter's live-streaming service Periscope.
"What happened today is senseless," Cleveland Police Chief Calvin Williams said at a news conference. "I know, Steve, that you have a relationship with some of our clergy in northeast Ohio. I encourage you to give them a call and then call us and turn yourself in."
Posts on Stephens' Facebook page said he had "lost everything" to gambling and wanted to speak to several people he named, according to NBC News, which saved the Facebook posts before they were removed.
The posts also said Stephens "killed 12 people today" during what he called his "Easter day slaughter" and would not surrender until he could speak to two women, including his mother.
"This is a horrific crime, and we do not allow this kind of content on Facebook," a Facebook spokesperson said in a statement. "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."
Stephens is an employee at Beech Brook, a children's behavioral health center in Ohio, a company spokesperson told ABC News. The suspect records video of an employee ID with Stephens' face and name on it.
Nancy Kortemeyer, a spokeswoman at Beech Brook, said Sunday night: "We were shocked and horrified to learn of this news today. We were notified that it was on Facebook, and we are waiting along with everyone else to hear if he has been abducted. Our hearts go out to the family of Mr. Goodwin, and we are hoping that the Cleveland Police will be able to apprehend Mr. Stephens as soon as possible and before anyone else is injured. We do not have any additional information at this time."
Family members of Godwin were in tears when they spoke Sunday with local reporters. "It feels like my heart is going to stop," one woman said.
The woman whom the shooter refers to, a girlfriend of Steve Stephens, is cooperating with investigators in the manhunt, according to Cleveland.com, which cited an unnamed senior law enforcement source.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)