A mass shooting may have been prevented when an employee at a Marriott hotel in Long Beach, California, reported that a disgruntled co-worker had threatened to kill workers and customers at the hotel, police said Wednesday.

The man, who had several high-powered weapons and hundreds of rounds of ammunition at his Los Angeles-area home, was arrested Tuesday, police said.

Rodolfo Montoya, 37, who was arrested at his home in nearby Huntington Beach, communicated the threat to someone he worked with at a Marriott hotel Monday evening, Long Beach police Chief Robert G. Luna said. The chief hailed the worker who helped get police involved, saying the warning likely saved lives.

"Thank God that employee decided to bring that information forward," Luna said at a news conference Wednesday.

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Police said they seized high-powered firearms, including one described as an assault rifle, hundreds of rounds of ammunition, 38 magazines that hold 30 rounds each and what was described as tactical gear from Montoya's home.

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.

Weapons and ammunition seized from a cook at a Los Angeles-area hotel who allegedly threatened a mass shooting. Long Beach Police Department via AP

Montoya was booked on charges of manufacturing and distributing assault weapons, possession of an assault weapon and making a criminal threat. He is being held in lieu of $500,000 bail, police said. The Los Angeles County District Attorney's Office is expected to decide on what charges he may face.

Montoya, a cook at the hotel near Long Beach Airport south of downtown Los Angeles, was said to be upset about issues with human resources and told a fellow employee about his anger and plans. The employee notified hotel staff of the threat, and police became involved.

"He's alleged to have said ... he was going to shoot up fellow employees and people coming into the hotel," Luna said. "So, he had a plan of shooting everybody that he saw in the hotel."

It was not immediately clear if Montoya had an attorney who could speak on his behalf. A phone number listed for a person under that name and age in Huntington Beach could not immediately be found.

Luna said Montoya does not appear to have any criminal history that would have prevented him from owning firearms, although possession of the gun described as an assault rifle, as well as the 38 30-round magazines allegedly found at his home, may be illegal under state law.

The chief said it is unclear how far Montoya had gone on his alleged plans. Police are working to determine when and where he acquired the guns and other items.

"How far away were we from this guy acting out, that's part of the questioning that we’re going through right now," Luna said.

In the weeks since back-to-back mass shootings in Texas and Ohio, a growing number of people accused of threatening mass violence have been arrested, including a Las Vegas man who allegedly wanted to attack Jews, an Ohio man who owned two AR-15 weapons and allegedly made threats against a Jewish community center, and an 18-year-old Ohio man who allegedly made online threats and had 15 rifles, 10 handguns and around 10,000 rounds of ammunition.

On Aug. 3 and 4, gunmen in separate incidents opened fire at an El Paso, Texas, Walmart and in a Dayton, Ohio, entertainment district, killing 31 people in all. Late last month in Gilroy, California, a 19-year-old gunman opened fire at an annual food festival and killed three people, including two children.