The students were leaving Benicia High School at about 11 p.m. after the 7:30 p.m. homecoming game against Fairfield's Vanden High School when the suspects approached them in an outdoor hallway near the administration building, police said.
Two of the suspects confronted one victim, while two other focused on the other, Lt. Mike Daley said.
The victims were forced to turn over their wallets and cell phones, Daley said. One suspect pushed what appeared to be a black, semi-automatic handgun into one victim's stomach, Daley said.
Three of the suspects then ran east and the fourth ran west through the school after a school administrator appeared, police said.
The suspects are described only as black males between 16 and 18 years old.
Detectives and the school resource officer are reviewing the surveillance video, Daley said.