SAN FRANCISCO (KGO) --Police in San Francisco are calling it a bizarre case after a complete stranger stabbed a man outside a bar.
There was no apparent motive and now authorities are concerned the man may strike again. Police released surveillance video in hopes of catching the suspect.
The incident happened a week ago around 1 a.m. in front of Durty Nelly's on the 2300 block of Irving Street.
A customer stepped out to text someone when a man, a stranger, stabbed him in the back as he walked past him. There had been no altercation and the victim was not robbed. Police say they can't find a motive.
"It was completely unprovoked. This person didn't know who this person was," said San Francisco police Officer Carlos Manfredi. "The suspect wasn't a patron in the bar. He was just walking randomly, saw the victim and took advantage and stabbed him and continued to walk away."
The surveillance video shows an Asian man 5'6" about 150 pounds wearing prescription glasses, holding a sharp object in his left hand, twirling it.
The victim described as a white male, didn't see him coming. The knife punctured his lung. He was taken to the hospital and has since been released.
Residents insist this is a safe neighborhood.
"In my mind usually when there is something like this, there is a motive or they are robbing the person or whatnot, so I'm shocked at what happened," said neighbor Ben Pepper.
Police worry the man in the video may attack again.
"We want to make sure he doesn't do it again," Manfredi said.
"I'm sorry it occurred but I think putting the word out there, putting the images out there is all that we can do," said another resident.
Police are hoping someone out there will identify him.