Two people have died and two others have life-threatening injuries after an argument at a Halloween party quickly escalated into a shooting early Sunday morning, East Palo Alto police said in a press release.

The incident occurred on Sunday morning at about 2:44 a.m. The East Palo Alto Police Department received notice of a ShotSpotter activation on the 2500 block of Pulgas Avenue; 911 dispatchers received multiple phone calls.

“Preliminary reports indicate there was a private adult Halloween party being held outside at the rear of (a) business complex, a dispute escalated into a physical altercation that quickly erupted into gunfire. The suspect fled the scene and is still outstanding at the time,” police said in their written statement.

Officers arrived on the scene in less than two minutes to find four victims with gunshot wounds. The Menlo Park Fire Protection District and American Medical Response ambulances arrived and personnel began treating the victims. Two people were pronounced dead at the scene and two others were taken to the hospital with life-threatening injuries. The deaths are the city’s first to occur in public since June 10, 2016.

Police identified one of the deceased victims as Eduardo Alvarado Sandoval, a 22-year-old Stockton resident. The San Mateo County coroner will identify the other person and release the name after notifying the victim’s family.