A Santa Clara County bus driver has been arrested and charged on suspicion of gunning down a co-worker in a bus yard over a gambling debt.

The Santa Clara district attorney’s office charged 33-year-old Duc Minh Bui on Wednesday with murder in the death of Regulus Teotico, 45, a fellow bus driver with the Valley Transportation Authority.

Teotico was found slumped over in his black Mercedes on Sept. 20 shortly after 9:30 p.m. in the Chaboya Yard employee parking lot in San Jose. Surveillance footage from the lot shows Teotico met with a man driving a white Nissan, according to court records. The man was later identified as Bui.

The footage shows that the two men got out of their vehicles and looked into the trunk of Teotico’s car, authorities say. Teotico then got back into the driver’s seat. Bui, who appeared to be wearing blue latex gloves and carrying a black bag or folder in his left hand, walked over to the passenger side door and opened it, homicide investigators say.

While standing outside of the car, Bui reached into the bag, pulled out a black handgun and fired several times at Teotico, according to authorities. Detectives found three .40-caliber shell casings at the scene.

Teotico had earlier asked a friend to meet him at the parking lot where he was planning to meet a co-worker who owed him money for betting on college and NFL football games, according to court records. Teotico said he wanted his friend there to make sure everything went smoothly.

In a joking manner, Teotico described the co-worker who owed him money as a “chubby Vietnamese guy,” according to homicide investigators. Earlier in the week, Teotico told his friend that his co-worker owed him money for sports betting.

When the unidentified friend arrived at the parking lot, he saw Teotico speaking to a man near a white vehicle, authorities say. As the friend parked his car outside of the lot, he heard two or three bangs from the direction of the parking lot. He then saw a white car drive past him heading south on South 7th Street toward Tully Road, investigators said. When the friend looked back to where Teotico was standing before, the white car was gone. The friend didn’t see the car pull out of the lot, but decided to follow the car that drove past him for a short distance before returning to the parking lot, according to investigators.

At the parking lot, the friend saw Teotico’s car door was open and found his friend sitting in the driver’s seat unresponsive, with blood coming out of his nose, investigators say. Teotico’s friend called 911 at 9:38 p.m. He had been shot several times and paramedics who responded pronounced him dead at 9:53 p.m. according to investigators.

Valley Transportation Authority managers who viewed the surveillance footage that captured the shooting identified the shooter as Bui, according to investigators.

Sheriff’s investigators served a search warrant at Bui’s home and found three firearms, including two .40-caliber Glock 22 handguns, authorities say. All three guns were registered to Bui and detectives also found an empty Glock firearm box with an obliterated serial number, according to court records.