US police assess rise in threat tips after 3 mass killings

This Aug. 21 photo shows 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, File)

LOS ANGELES — It had all the makings of a massacre. Six guns, including a Colt AR-15 rifle. About 1,000 rounds of ammunition. A bulletproof vest. And an angry Southern California man who threatened to kill his co-workers at a hotel and its guests.