Santa Monica College was put on lockdown this afternoon after a gunman opened fire on the campus.
At least four victims have been hospitalized, according to UCLA Medical Center.
A suspect was in custody, California Highway Patrol Sgt. Denise Josline said. She could not provide a name or description of the suspect.
The college campus remained on lockdown as of 2:30 p.m. PT.
Santa Monica College student Sam Luster was preparing for a presentation in the school's library when he heard gunfire.
"We didn't know what was happening until all the students at the entrance of the library started running down towards the bottom of the library," Luster told ABC News Los Angeles station KABC.
Luster took cover under a desk before moving towards an exit. He said he heard multiple gunshots near the exit.
Authorities were searching for a possible second shooter out of an abundance of caution. This was part of protocol in active shooter situations, but authorities also received a call that an armed subject was seen on campus after police had a suspect in custody.
Police were investigating whether a nearby arson incident was related to the shooting. Two people were found dead in that house fire, according to the Los Angeles Fire Department.
In 911 calls, the shooter was described as armed with several weapons and possibly a long gun or shotgun.
Three female victims from the shooting were transported to Ronald Reagan UCLA Medical Center. Two of the women were in critical condition and one was listed in serious condition.
A fourth female victim was taken to UCLA Medical Center Santa Monica and was listed as in good condition.
Authorities said that one of the wounded people was on a bus that was fired upon.