One man was arrested at about midnight Friday on suspicion of possessing an illegal weapon.
The unidentified man used a sock with a padlock in it during a gang-related attack, Sgt. Brian Martinez said.
Police responded to a report of people fighting on Elm Street at Adelle Street in North Livermore.
"The report came out with one subject swinging a sock with something heavy in it," Martinez said.
An officer arriving on scene stopped a vehicle leaving the area.
"We couldn't find any victims but one of the subjects in the vehicle was in possession of a sock with a padlock in it," Martinez said.
The four people in the vehicle claim to be affiliated with the , Martinez said.
A short time after the arrest police were contacted that two males checked in to ValleyCare Medical Center in Pleasanton.
Martinez said the two males suffered injuries as a result of the North Livermore fight.
"They described the guy we arrested as the person who struck them," Martinez said.
The fight is still under investigation.
Friday's incident is the latest in a string of gang-related crime to hit town this month.
On March 19, a by a rival group on the 3800 block of Silver Oaks Way. His injuries are non-life threatening and he is expected to survive, officials said.
Police continue to investigate a on Chestnut and North I Streets that left two people injured on March 13. The injuries were not life threatening, police said.
On March 8, a 17-year-old boy was confronted by an unknown person and in the area of the March 13 shooting.
The teen was cut on his arm but did not suffer major injuries. He was uncooperative with police, and officials continue to search for the suspect.