The shooting happened just after 2 a.m. on Monday in the parking lot of the Circle K at D Street and Vineyard Avenue in Ontario.
"The hotels in the area could hear gunshots in the area," said Anthony Ortiz from Ontario police. "One of our patrol units rolled up on scene, and could see a black Chevy Malibu leaving the scene."
Officers stopped that car. Inside was a man suffering from a gunshot wound and a female companion. It's believed they were driving away from the third person in their group who was shot and killed.
"He was in the parking lot, bleeding from the head," said Ortiz. "We discovered he had been shot, and he did die as a result of that gunshot wound."
Police say the group of people on the other end of the argument sped away in a black SUV. It's unknown how the argument started or why.
"It was a public parking lot," said Ortiz. "And at that hour of the morning thank God there was not that many people out on the street walking around."
Police aren't saying whether the shooting is gang related.
Police say there is extensive surveillance video of what happened, and there are good pictures of the suspects who are still at large.
"We are working some very solid leads at this time," said Ortiz. "Hopefully those things will manifest and we'll bring everybody to justice as we want to."
Police are looking for at least two suspects. If you have any information call Ontario police at 909-395-2001.