Alvin Chen, 43, cried at times as he told The Associated Press about the chaotic shooting inside a UPS warehouse Wednesday that also left Lam dead after he killed himself and left another driver with a gunshot wound.
Although police have suggested Lam might have felt disrespected by other workers, Chen said it would have been out of character for any of the three men who were killed to have done so. It would have been especially out of character for two of the drivers who were his close friends, Chen said, adding that he knew of no animosity between them and Lam.
"I'm heartbroken. I can't understand why this happened," Chen said, a pair of crutches nearby. The workplace deaths of the UPS drivers — Wayne Chan, 56; Benson Louie, 50; and Mike Lefiti, 46 — shocked San Francisco and stunned UPS workers. Chen said he felt compelled to speak out about the dead drivers to speculation that Lam might have been motivated to open fire because of bullying.
A San Francisco Police Department official has said Lam appears to have felt disrespected by co-workers, but did not know if that motivated the shooting. The officer spoke on condition of anonymity because the officer was not authorized to speak publicly about the investigation.
Chen said Lam never indicated before the shooting that he had problems with other workers, and said he had a friendly chat with Lam about their routes on the Monday, two days before the shooting. They spoke Cantonese to each other, although Lam's ethnicity is unclear. Records show Lam moved to the United States as an infant from Thailand.
The day of the shooting started like any other work day, Chen said, with drivers doing warm-up stretches and listening to company announcements before they were scheduled to climb into their trademark brown UPS trucks for the day.
Chen said he was standing in his usual spot, by Chan and Louie, when he heard a loud pop like a firecracker behind him. He dismissed it as a prank but turned and saw smoke. He heard a second pop and felt pain. When he looked down, he saw blood pouring down his leg.
Chen got into the cab of the truck closest to him, hoping to hobble out through the truck's rear door and slip down a hallway and into the street. He was about 60 feet (18 meters) from the exit when he saw Lam blocking his path, scanning the room as if looking for someone.
"But I don't know who he's looking for," Chen said. He turned back, checking to make sure he wasn't being followed. He encountered another UPS driver hiding behind a truck. That's also when Chen noticed a body on the ground. It was his friend Wayne Chan.
Terrified to stay put, Chen decided to find a hiding place and went into an empty office, bleeding as he ran. "I knew if I don't run, I may get killed," he said. Police eventually found Chen on the floor behind a desk, unable to stand up and with his hands raised as officers had demanded. Chen found out when he was being treated at a hospital that Louie had also been killed.
"I keep dreaming every night when I close my eyes, that moment. It's really scary, I can tell you," he said. "And you don't want it to happen next to you and around you. It's a very, very bad experience."
Chen said he does not know how he feels about Lam, although it's more sadness than anger. "I'm not even thinking like I hate him or not," he said. "I'm not."
AP reporter Linda Wang contributed to this report.