(ABC NEWS) -- A woman is dead and seven people injured after a gunman opened fire at a birthday pool party at a San Diego apartment complex Sunday, police said.

The alleged gunman, identified as Peter Selis, 49, was shot and killed by police, San Diego police said.

Numerous calls were made to 911 around 6 p.m. local time to report the shooting at the gated pool area of the La Jolla Crossroads apartment complex, police said.

Maniza Sheikhani, who was at the complex at the time, told ABC News, "I heard what sounded like fireworks, I wasn't sure what it was. And then I smelled smoke and I turned around and I heard people screaming and running ... I just ran. And I heard other people screaming, 'There's a shooter, there's an active shooter.'"

Selis, who was allegedly armed with a high-caliber handgun, lived in the apartment complex, police said.

Police said eight victims, all adults, were hospitalized and one later died.

It is not clear if the suspect knew the victims, police said.

Authorities do not know the motive and are interviewing witnesses, police said.

San Diego Mayor Kevin Faulconer called it a "horrific and disturbing act."

This story is developing. Please check back for more updates.