The Associated Press and Bay City News contributed to this report.
The shooting, which occurred at about 1:30 p.m. in a campus parking lot, left an 18-year-old man injured, San Bruno police Cmdr. Marc Catalano said.
Catalano said the shooting was preceded by an altercation between two groups of people. He said the shooting was an isolated incident.
The student was shot in the buttocks, Barbara Christensen, San Mateo Community College District director of community and government relations, said. The schools student newspaper, The Skyline View, said on its Web site the victim was conscious and breathing before being taken away.
Student Edward Reyes, 21, said he was inside the school's Learning Center shortly before 2 p.m. when the shooting victim, a male, appeared.
"He barged right in screaming, 'I got shot,'" Reyes said.
Reyes called 911. He said it appeared the victim had been shot in the behind.
Jennifer, a 19-year-old student who refused to give her last name, said she was coming out of class when the shooting occurred.
"I heard a lot of popping noises," she said.
She said she saw three males running out of the Pacific Heights parking lot near Building 5. One had a gun and wore a black hooded sweatshirt, she said.
The three ran toward the main campus from the parking lot, she said.
A male student, who declined to give his name, said he saw a male victim on a stretcher. He did not know the victim's condition but said he was blinking.
Fall semester classes started at the school on Aug. 19, said Christensen. About 10,000 students are enrolled this semester, she said.
Christensen said a text message had been sent to students who signed up for emergency text message alerts. She did not know how many had signed up but said the number is "substantial."
The victim was reportedly taken to San Francisco General Hospital. The school was on lockdown and classes were cancelled for the day.