Three people have been confirmed dead and nine others injured following a shooting during a party in Long Beach, California.

Regional firefighters arrived on the scene at approximately 10:44 p.m. local time, discovering that 12 people had been shot during what has been described as a costume party. The nine injured were transported to nearby hospitals. According to CBS Los Angeles, the suspect "fled the scene," though it was not immediately known whether the person did so on foot or in a vehicle.

"It looks like it was a party, some type of a Halloween-type costume party and that seems to be where the shooting occurred," Long Beach Fire Department pubic information officer Jake Heflin said, per NBC News.

While other reports cited the suspect as having fled the scene, the Long Beach Police Department has said that—due to the nature of the active investigation—not much was known about the suspect, including whether the person acted alone.

"We don't know if there is just one suspect or multiple," Long Beach Police public information officer Jennifer De Prez said. The 12 victims have been further described as being in their mid-20s, with the three who were killed during the incident confirmed to be men. Of the nine injured, as many as five sustained possibly life-threatening injuries.