The alleged gunman in this morning's triple homicide at a UPS sorting and distribution center in San Francisco's Potrero Hill neighborhood has been preliminarily identified as UPS employee Jimmy Lam. ABC 7's Dan Noyes reports on the shooter's name via a fellow UPS worker, who further told him that Lam "had it out for a manager."

Three victims have been confirmed dead in the shooting, which apparently happened during a shift change around 9 a.m. Wednesday, with two more injured and being treated at SF General, according to the Chronicle. According to one early account, the shooter opened fire during a morning meeting among drivers. About 350 people work at this particular UPS facility, and a dramatic photo emerged in the minutes after the shootings via neighbor Kevin Wood on Twitter, showing a group of UPS employees who had escaped to a rooftop parking lot and were waving to be rescued.

After the shootings, Lam reportedly shot himself in the head with an assault pistol when he was confronted inside the building by police. A total of two weapons, including another handgun, were recovered from the scene.

According to NBC Bay Area, Lam was 38 and resided in the Richmond District. ABC 7 says he was estranged from his wife, and had children.*

Neither the SFPD nor UPS has confirmed the identity of the shooter.

The Chronicle has identified one of the victims as 46-year-old Mike Lefiti of Hercules.

The building was secured at 10:32 a.m., as the SF Business Times reports, but it wasn't for several hours that the SFPD lifted the shelter-in-place order in the neighborhood as they continued to search the facility.

The SFPD has said they believe this was an isolated incident and not related to terrorism of any kind.

State Senator Scott Wiener issued a statement Wednesday saying, "We can’t continue to allow this level of gun violence to become the new normal in our nation. Today we mourn the San Franciscans who were murdered in cold blood and send positive energy to the survivors of these shootings. Tomorrow we get back to work to enact common sense gun control legislation."

SF Supervisor Malia Cohen, in whose district the incident occurred, issued a statement saying, "I am deeply saddened by the tragic shooting that occurred this morning at the UPS facility at 17th and Utah Streets. My thoughts go out to the individuals and families who have been impacted, and I want to express my deep appreciation to the members of SFPD, 911 and San Francisco General Hospital, who addressed this incident quickly and efficiently."

Sadly, the incident unfolded less than five hours after a brutal, targeted shooting in Alexandria, Virginia in which multiple Republican members of Congress were wounded. Rep. Steve Scalise remains in critical condition because of his injuries.

Previously: [Update] Shooting At UPS Center On Potrero Hill, At Least Three Killed

* This post has been corrected to show that Lam lived in the Richmond District, not the Sunset, and that he did not live with his children.