SUNNYVALE, CA - A California UPS worker who threatened a mass shooting had multiple tactical rifles and 20,000 rounds of ammunition at his home when it was raided by police.

The Sunnyvale Department of Public Safety says Thomas Andrews, 32, was reported to police Sunday for sending threatening text messages to his employer, saying that he was planning a mass shooting at the UPS facility in the city.

“He alluded to a mass shooting in his text messages,” Sunnyvale police Capt. Dan Pistor told the Associated Press. “I definitely think we avoided a tragedy.”

Officers immediately began searching for Andrews, who they had discovered was the registered owner of four handguns and a rifle. Police spotted Andrews driving late Sunday evening and tried to pull him over, but he led officers on a pursuit on Highway 101.

Andrews was stopped and taken into custody with help from California Highway Patrol.

Detectives who searched his home found over 20,000 rounds of handgun and rifle ammunition along with several high-capacity magazines, five tactical style rifles, a shotgun, three handguns and body armor.

Police said that several tactical backpacks containing ammunition were “staged” at the front door of Andrews’ home.

Andrews has been charged with making criminal threats, evading police, driving under the influence and multiple weapons violations.