California police say a hotel worker may have prevented a mass shooting after the worker reported th
California hotel employee 'prevents mass shooting'
Acting on the tip-off, officers arrested a 37-year-old man who was found to have high-powered weapons and ammunition at his Los Angeles home.
It comes amid a wider FBI effort to prevent such shootings.
That followed attacks in El Paso and Dayton that killed 31 people.
Since then US authorities say they have foiled a series of alleged plots to carry out attacks, some of which would have targeted minority groups.
The FBI has reportedly instructed its field offices to conduct threat assessments and has also urged the public to report threats or suspicious activity.
What happened in California?
Rodolfo Montoya made the threat to someone he worked with at a Marriott hotel near Long Beach airport, Long Beach Police Chief Robert Luna said.
"Thank God that employee decided to bring that information forward," he told reporters.
Police said they seized multiple firearms including an assault rifle, hundreds of rounds of ammunition and tactical gear from his home in Huntington Beach. The assault rifle and high-capacity magazines were illegal in California, a statement said.
Early investigations revealed that Mr Montoya was upset over "human resource issues", police said.
He had "clear plans, intent and the means to carry out an act of violence that may have resulted in a mass casualty incident," Chief Luna said.
What other alleged plots have been foiled?
On Tuesday a man was jailed in Seattle, Washington, after the FBI said he threatened to kill Hispanics in the Miami area. Eric Lin, 35, sent a message to a Hispanic woman threatening her and her family. He also expressed support for Adolf Hitler, said he believed President Trump would "launch a racial war and crusade" and called for Hispanics, black people and members of other ethnic groups to be killed or sent to concentration camps.
In Wisconsin, a man in Eau Claire was charged on Tuesday with making a terrorist threat and disorderly conduct after he told colleagues he would "shoot up the place" where he worked. Kevin Pinkham, 31, denied making the threat, but admitted texting his girlfriend that he was going to kill everyone.