When police arrived, they shot at the dog but missed, then a few blocks later, officers fatally shot the animal.
"I heard guys arguing, and I hear a 'Stop, stop,' and didn't know what was going on, and then next thing, another guy running, and I hear the separating of the dogs, and then later on, the cops shoot it," said witness Christine of Long Beach.
According to witnesses, police had no choice but to shoot the dog.
"The dog went after the cop apparently," said an unidentified Long Beach resident.
A man was taken by ambulance to the hospital with non-life-threatening injuries.
Residents in the dog-friendly neighborhood said they've had trouble with the owner and the pit bull before and were afraid that one day it would turn violent.
"It's horrible, but if the dog bit someone, it's vicious, it should be shot," said Michael Ruben of Long Beach.
It is unclear whether the owner of the pit bull will face any charges.
The Long Beach Police Department is investigating the incident.