(10-03) 07:49 PDT SAN LEANDRO -- At least two gunmen opened fire on a group of people leaving an unlicensed warehouse party in San Leandro early Sunday, killing a teenage girl, a 19-year-old woman and a 23-year-old man while wounding three others, police said.

The shooting on the 2600 block of Alvarado Street was reported by a cell phone caller at 1:20 a.m. Officers who responded found multiple gunshot victims, and, along with bystanders, began trying to perform life-saving measures, said police Sgt. Doug Calcagno.

Three people were pronounced dead in the parking lot of Gardco Industrial Park, which houses several businesses. Family members and friends identified them as Leneasha Northington, 16; Shanice Kiel, 19; and Joshua Alford, 23.

The windows of a green Ford Explorer belonging to Kiel's father were shattered by gunfire. The slain victims were found just feet from the vehicle.

Two others were taken by ambulance to a hospital, and a final victim was driven to a hospital by a friend, Calcagno said.

The victims were shot during a "tattoo party," in which the host of the party hires a tattoo artist to come to the location, said Sherri-Lyn Miller, a San Leandro print shop owner who works with crime victims and spoke with some of those involved.

Alford is a warehouseman whose girlfriend is six-months pregnant, Miller said. Kiel, a student at San Francisco State University, would have turned 20 next month. She worked at a clothing store, made jewelry, wrote poems and wanted to become a fashion designer, said her aunt, Betty Bryson.

"She was a lovable person," Bryson said. "She got along with people with no problem."

Bryson said she was sickened by the violence. "It's something that should never happen," she said. "It's sad that our teenagers can't go out and enjoy life and everything without people doing drive-bys or somebody getting shot over something ridiculous. It's a senseless thing that happened."

The assailants fled in an unknown direction, Calcagno said. No arrests have been made, and investigators do not yet know the motive for the shooting.

The party, inside a warehouse in an office park, was advertised on the Internet - including Facebook - and drew a large crowd, Calcagno said. The event ended just before the shooting.

Given the size of the event, and the fact that guests had to pay $10 to $20 for admission, the party's organizers would have needed a permit, Calcagno said. Police have found no such permit on file with the city. It's not known yet, Calcagno said, whether alcohol was served.

Efforts to reach the owner of Gardco Industrial Park were unsuccessful.

The organizing of the party is "part of the investigation," Calcagno said. "People are putting on parties and going to different locations, many times without proper permits. They rent out a space, and they have a party, and sometimes they end badly.

"This is tragic," the sergeant said. "We always look for a motive, but it's never acceptable that three people lost their lives in a parking lot in San Leandro. It's awful, and a tragic thing for all of their families. We're eager to find out who's responsible for it."

Police ask anyone with information to call investigators at (510) 577-3278. Callers may remain anonymous.