Several people witnessed a violent confrontation at the Ocean Beach Branch Library Monday afternoon.
Security guard Jesus McClaskey said the trouble started over some quarters.
"A man started bugging people for a quarter," McClaskey said. "Nobody has any money so he started screaming and yelling at everybody."
McClaskey said when the man started cussing and screaming at customers, including parents and their children, they removed him from inside.
"He said he's going to kill people," McClaskey said. "Kicking the door real bad."
McClaskey and others actually barred the door so the man could not get back inside. Cell phone video shows the man cussing, kicking the door, stumbling, and screaming.
"And he said 'This place is going to be bombed, but before I bomb it everybody is going to be dead,'" McClaskey said.
Branch manager Matthew Beatty says they called the police and filed a report.
"I was really bothered because we had families in the library, we get lots of small kids here," Beatty said. "That was the loudest incident we've had since I've been here and I've been here a dozen years."
Beatty also says the man will be suspended indefinitely from the library.
10News sent San Diego police the cell phone video, and a spokesperson said they sent it to Ocean Beach officers, who likely know the man and will be able to find him soon.