A failed relationship is the apparent motive behind the San Diego swimming pool shooting spree

SAN DIEGO (CNN) -- Despondent over the end of a relationship, a gunman entered the pool area of his San Diego apartment complex Sunday and began shooting randomly at people gathered for a birthday party, authorities said.

At some point during the shooting, 49-year-old Peter Selis took a seat in a lounge chair, pulled out his cell phone and called his ex-girlfriend to tell her he shot two people, San Diego Police Chief Shelley Zimmerman said in a news conference Monday.

Selis kept her on the phone as he continued shooting, killing one woman and injuring six before police fatally shot him, Zimmerman said. Another person was injured while fleeing the La Jolla Crossroads apartment complex.

On Wednesday, a source with knowledge of the investigation identified the woman who died as Monique Clark.

A cell-phone video appears to show the gunman reclining in a chair beneath an umbrella, legs crossed as he reloads the gun in his lap, takes aim and pulls the trigger.

Though Selis was white and some of the victims were people of color, Zimmerman said there was "zero information" to suggest the rampage was racially motivated.

"The victims were targeted for no reason other than their mere presence," Zimmerman said. "What started as a celebration of a friend's birthday turned into a tragedy of epic proportions for all those in attendance."

'He didn't say a single word'

The first 911 call came in at 6:08 p.m., reporting two people had been shot, Zimmerman said. The second caller described hearing five to six gunshots and seeing someone outside with a gun.

As police responded to the calls, officers in a helicopter above the complex directed ground units to the suspect, she said. Three officers confronted the shooter, Zimmerman said. He pointed his weapon at them, prompting an exchange of gunfire that killed Selis at the scene.

Six survivors were sent to area hospitals with gunshot wounds. Another person suffered a broken wrist, a broken hand and a concussion from climbing a fence during the shooting. All are expected to recover. Authorities initially identified the shooting victims as four black women, two black men and a Hispanic male. Investigators learned that one of the victims initially reported to be a black female was actually white.

The party started about three hours before the gunman showed up around 5:30 p.m., guest Demetrius Griffin wrote on a fundraising site, where the victims are accepting donations for medical expenses.

Something about him was "strange," Griffin said in the post -- all he had was backpack, no book or anything else to suggest "a day at the pool."

The "birthday boy" approached the man to invite him into the party, Griffin said. The conversation did not last long. The man pulled out a gun and shot Griffin's friend in the chest before turning his weapon on the crowd.

"He was very docile. In his facial expression, no smiling, laughing, talking," Griffin told CNN Monday. "He let off eight rounds, reloaded, let off another eight, reloaded again."

As people began scrambling and screaming, the shooter "didn't say a single word," he said.

Partygoer Haley Thames said she and her friend Lauren Chapman were among those who ran for cover. As they ran, they noticed two women who had been shot and were lying in a pool of blood. One of them was Thames' cousin.

"I turn around and saw family on the ground, and it became all about that," Thames said.

Chapman said they helped lead the women out of the pool area to safety. When they reached the street, Chapman flagged down an SUV. The driver cleared out his car and drove the women and another victim to the hospital, Chapman said.

San Diego Fire Chief Brian Fennessy later identified the driver as a security guard for the apartment building.

At a news conference Monday afternoon, survivor Thomas Blea thanked the driver and the first responders who came to his aid.

"It was a terrible experience that we went through, but I'm glad that I'm all right, and I'm glad that most of my friends are all right," he said.

What we know about the shooter

Selis broke up with his girlfriend days before the shooting, Zimmerman said. Family members described him as depressed, but said nothing in his behavior suggested this kind of violence.

"It is very clear that he was despondent over the breakup," the police chief said. "It is apparent that he wanted his girlfriend to listen in as he carried out his rampage."

Detectives are still looking into Selis' background, she said. He has no criminal history and one handgun registered in his name.

Facing significant debts, he filed for bankruptcy in 2015. He listed his occupation as car mechanic, according to a petition filed in US Bankruptcy Court in the Southern District of California.

"This was a truly horrific and disturbing act. We pray for the victims and thank our first responders. Our city rejects this senseless violence," San Diego Mayor Kevin Faulconer said at a news conference.

Shots ring out in placid neighborhood

The apartment complex, La Jolla Crossroads, is located near the University of California San Diego campus. Residents described the complex as typically quiet, a place that college students, physicians and military families, among others, call home.

In a span of about 30 minutes, apartment residents heard gunfire, sirens and the screams of those near the main pool, said resident Susan Berry, who was at the property but did not witness the shooting.

"People are shocked because it's an affluent neighborhood," Berry said.

When asked how he would characterize what happened, Griffin said he would not call it a terrorist act. "But it's terror," he said.

Chapman agreed that the most appropriate word to describe what happened was "terror." A junior grade lieutenant in the US Navy, she said she expects to come under attack in war zones abroad, not at home.

"I dedicate my life serving my country understanding that my life is on the line when I'm out there. But at no point in time would I think an act of terror would take place at home in the way that it did."