The incident happened Sunday as seven people were shot, one fatally.
The man who sprayed a California pool party with bullets over the weekend called his ex-girlfriend to make her listen to the gunfire, cops have revealed.
The woman, who was not identified, had just broken up with him, police said.
Video from the scene shows the gunman, 49-year-old Peter Selis, relaxing in a lounge chair as he appears to reload, pointing his gun and firing.
One witness said Selis "was sitting there with a beer in one hand and a gun in the other."
Seven people were shot — one fatally — during the rampage at an upscale apartment complex where apartments rent for $4,000 a month in University City, near La Jolla.
Drew Phillips, a guest at the pool party, is a former co-worker of the gunman.
"Nothing was going on and he just opened fire on innocent civilians," he told Inside Edition. "We heard nothing. No monologue, no nothing."
Phillips said he didn't appear to be intoxicated and he believed his friends offered him the beer he was holding when he was opening fire.
The gunman was heard telling people: "You can leave or stay here and die."
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The break-up with his girlfriend was said to have triggered the rampage. All of his victims were black or Hispanic, but authorities said race was not believed to be a factor.
The gunman was killed in a hail of gunfire after police responded to the scene.
Selis is a former auto mechanic at a San Diego Ford dealership. Bankruptcy papers filed in 2015 revealed he had amassed $400,000 in debt.
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