A motive for Wednesday morning’s shooting at a United Parcel Service (UPS) facility in San Francisco, California was still not clear two days after the tragedy in which four employees were killed, including the alleged shooter, Jimmy Lam. However, coworkers who knew Lam sensed he was facing depression and personal struggles, according to statements given to the media.

Lam had worked at UPS for 18 years and had appeared to be on friendly terms with the three victims, Shaun Vu, a senior driver for the company, told the Associated Press. Vu encouraged Lam to seek help with depression stemming from an apparent dispute between him and his girlfriend over visitation rights with their child. Lam then took several months off work, but was clearly still troubled upon returning.

The shooting occurred during a morning pre-delivery meeting at the facility in the Potrero Hill district of the city. Lam reportedly shot Benson Louie, 50, first before killing Wayne Chan, 56. The third victim, 46-year-old Mike Lefiti, known as Big Mike, was killed as he fled the building. Louie and Lefiti had both worked at UPS for 17 years, while Chan had been with the company for 28 years. Two more people were wounded in the attack.

Some reports suggested that Lam had a dispute with a manager, but none of those killed were in management. When police entered the UPS building, Lam shot himself and later died in hospital.

Joseph Cilia, a union official with the Teamsters Local 2785, said Lam had filed a complaint that he was working excessive overtime. He suggested that anger in Lam had been bottled up leading to Wednesday’s shooting, according to the local CBS affiliate.

Cilia said that excessive overtime was standard at the UPS facility, but claimed, “Most drivers don’t mind the 9.5, 10 hours,” before adding that “It’s the 11, 12, and 13 [hour days] that interfere with their life.”

Other employees painted a far grimmer picture of work at the facility, with some calling the atmosphere “hostile.” An employee fearing retribution from the company anonymously told the San Francisco Examiner, “Before this, there [were] problems with management, how they talked to people and treated people. He’s (Lam) not the only one. I think he’s not the only one on edge.”

WSWS reporters talked to UPS workers and neighbors who spoke affectionately of the three victims at a memorial outside of the facility. One worker, 34, who has been with UPS for three years, dismissed reports that Lam may have been bullied by the victims. “I read on the news that Jimmy was being bullied. There’s no way one of them was bullying him, those three were the nicest people you could meet. Big Mike treated me like he was my best friend, even though he barely knew me. They were my mentors,” he stated.

Sherwin, a friend of Louie and Chan for more than ten years, also stopped by the memorial. Employed in administration at a nearby school, he heaped praise on his friends saying, “They would figuratively and literally give the shirts off their backs. These two guys were family men, outstanding folks.”

The city of San Francisco is a major contradiction, with high rent and housing costs alongside declining living conditions. Just outside the Potrero Hill UPS, a large homeless encampment stretches down several streets, just one of the most visible signs of the social crisis in San Francisco.

Others who stopped by the memorial spoke on those conditions. UPS worker Jarrel complained that fights and carjackings in the area were not uncommon. “I appreciate my job, but it’s not safe here and this [shooting] was proof.”

Deante, 20, a construction worker, expressed his sympathies for the victims. He also expressed support for those struggling with mental illness, saying, “Employees should be able to see therapists for depression and receive help with that.” He continued, “There are shootings in this area every once in a while, a little bit of gang violence, but this was the worst incident I can remember.”

Hardly a day goes by in the United States where there is not a mass shooting of some kind. As of Wednesday, there had been 154 such incidents this year, although that number has already grown. Most recently, four people were killed and a fifth left in critical condition by a gunman in northern New Mexico on Thursday. Damian Herrera, 21, was arrested that evening after allegedly shooting three family members and two more people he encountered while attempting to flee police.