(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.

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