Police say a love triangle may have led to a shooting that left one man dead and another wounded in Fullerton on Wednesday afternoon.

Witnesses told NBC4 that they ran for cover when bullets began flying in broad daylight.

"When I was pulling up to start my sweep area, they were outside of the car arguing," Robert Castenada, a Fullerton street sweeper who witnessed the shooting, said. "When I got to the corner here I just heard the shots go off - maybe five, six, seven shots."

The shooting took place about 1:30 p.m. at Harbor Boulevard and Ash Avenue (map), according to the Fullerton Police Department.

Officers said a woman was driving with her ex-husband riding in the backseat and new boyfriend in the front passenger seat.

Castenada said he heard yelling, then watched a shoving match that spilled out on to the street.

The ex-husband, who police say was armed with a semi-automatic gun, opened fire on the boyfriend.

The boyfriend was struck multiple times.

Police said the semi-automatic gun can hold 10-16 rounds, and when they found it, it was empty.

The ex-husband then turned the gun on himself, police said.

Both men were taken to the hospital, the Fullerton Fire Department said.

Police said the shooter died, and the passenger was in critical condition.

"I saw a lot of blood. I saw a cop pushing on the guy's chest, you know to bring him back. One ambulance was there also," witness Joanna Renteria said.

Police Sgt. Katheryn Hamel said a dispute between lovers may have led to the shooting.

Officers were interviewing the woman, who described what happened. Officers also said the shooter did not fire upon the woman.

Irene Moore contributed to this report. Refresh this page for updates on this developing story.