(KRON) -- A SWAT team found armor-piercing ammunition inside a Richmond man's home after the man allegedly threatened to carry out a mass shooting, police said. The South San Francisco Police Department said the man threatened to target a victim's workplace in South San Francisco. "Detectives worked diligently on the investigation as the suspect continued to make threats against the victim," the police department wrote. After a search warrant was granted, the North Central Regional SWAT Team entered the man's house. (Photo courtesy South San Francisco Police Department) "During the search of the residence officers located armor piercing ammunition. The suspect was placed under arrest for violations of criminal threats," the police department wrote. Police did not release the man's name. He was booked into a San Mateo County jail.