CNN  — 

A hotel cook apparently upset over human resources issues has been arrested for allegedly planning a mass shooting of his coworkers and guests at a Marriott property in Long Beach, California, city police said.

A tip from a colleague led police to arrest Rodolfo Montoya, 37, at his Huntington Beach home, Chief Robert Luna said at a news conference Wednesday.

Police seized firearms, hundreds of rounds of ammunition and tactical gear, including high-capacity magazines and an assault rifle, which are illegal to possess in California, police said in a news release.

“Suspect Montoya had clear plans, intent, and the means to carry out an act of violence that may have resulted in a mass-casualty incident,” Luna said.

Montoya pleaded not guilty Thursday. His attorney did not offer a statement after court.

Montoya faces two counts of felony criminal threats, one count of dissuading a witness and another charge of illegal possession of an assault rifle.

More than two dozen people have been arrested over threats to commit mass attacks since massacres this month in El Paso, Texas, and Dayton, Ohio. Just after the shootings, the FBI director issued a directive for agency offices nationwide to conduct a new threat assessment.

Montoya doesn’t appear to have a criminal history that would prevent him from legally owning the types of guns allowed in California, Luna said.

He is being held on $500,000 bail at the Long Beach City Jail. A judge denied a motion to reduce bail.