A Long Beach hotel worker who had an arsenal of weapons at his home was arrested after telling a colleague he planned to wreak havoc at his workplace, authorities said today.

Officers found high powered firearms, hundreds of rounds of ammo, tactical gear, assault rifles and high-capacity magazines when they searched the Huntington Beach home of 37-year-old Rodolfo Montoya on Tuesday, according to authorities.

Montoya had clear plans and the ability to carry out “an act of violence that may have resulted in a mass casualty incident,” according to police.

“That is terrifying,” said Imran Ahmed, the general manager of the Long Beach Marriott, at 4700 Airport Plaza Dr., where Montoya worked as a cook.

Montoya’s coworkers were instrumental in stopping the potential attack, police said.

According to Ahmed, Montoya told one of his colleagues of his plan on Monday. When that coworker informed Ahmed, he immediately called police, who quickly sent multiple officers to the hotel.

At one point during a news conference today, LBPD Chief Robert Luna turned and directly addressed Ahmed.

“Sir, you saved many lives, not only of your employees but any customers that may have been at the Marriott when this guy decided to show up and carry out his threat,” he said.

Luna said Montoya was upset about some “recent workplace activity having to do with HR.” He told a fellow employee he planned to shoot up his coworkers and others coming into the hotel, Luna said.

“He went into somewhat of a description of what he was going to do and the tools he was going to use to do it, which he described very well because we have them right here on this table,” Luna said.

Police did not find Montoya at the hotel when officers flooded it Monday afternoon.

“There were so many cops in the hotel, our guests were getting nervous,” Ahmed said, crediting the LBPD for its response.

It’s not clear yet when he allegedly planned to carry out the attack, but police served a search warrant at Montoya’s home Tuesday and arrested him there, Luna said.

Montoya was a reliable worker, but he was somewhat unapproachable, according to Ahmed.

“He wasn’t a model employee but he never called out,” he said. Montoya even won an award for never missing a shift last year, Ahmed said.

Marriott workers have been trained to handle threats and other suspicions situations, according to Ahmed, who credited them and police for acting quickly.

“Otherwise this could’ve gone sideways very quick, very fast,” he said.

Montoya is being held on $500,000 bail, according to jail records. He’s being held on suspicion of manufacturing and distributing assault weapons, possession of assault weapons and making criminal threats, police said.

Luna said police are still investigating exactly how the weapons were obtained.

Montoya doesn’t appear to have any any criminal history that would have prevented him from owning firearms, but police suspect the some of the guns and the dozens of 30-round magazines he allegedly had may be illegal, Luna said.

“We’re certainly living in dangerous times,” said Mayor Robert Garcia, who added that more needs to be done to keep dangerous weapons out of the hands of the wrong people.