A man whose car contained a cache of weapons and bomb-making materials has been arrested after he told police he wanted to "harm" the Los Angeles Gay Pride parade, authorities said.
James Howell, 20, was detained in nearby Santa Monica with multiple weapons, ammunition and bomb-making materials in his car, which had Indiana license plates, police said.
The arrest came just hours after Omar Mateen, 29, opened fire inside a nightclub in Orlando, Florida, and was shot on the scene after police stormed the building.
The Islamic State has claimed responsibility for the attack, which left 50 people dead, and a further 53 people injured.
Santa Monica police chief Jacqueline Seabrooks said on Twitter that Howell told officers about "wanting to harm (the) Gay Pride event," in reference to the annual L.A. Pride parade that took place in Hollywood on Sunday amid beefed up security.
Santa Monica police said in a statement that Howell was arrested after a resident reported a prowler knocking on their door and window at around 5.00am.
When officers responded, they found Howell sitting in a car with three assault rifles, high-capacity magazines and ammunition, the statement said.
"Additionally, officers discovered a five-gallon bucket with chemicals capable of forming an improvised explosive device," it added.
Seabrooks said there was no known connection between Howell and the carnage in Orlando, Florida - the worst mass shooting in US history.
Authorities said they had considered calling off the parade but then decided to go forward while beefing up security, including placing undercover police in the crowd.
The march went ahead without incident.