A small device thought to be filled with dry ice exploded at Los Angeles International Airport late on Monday, the second one to detonate at the transport hub in 24 hours, police said.
No injuries or damage were reported and officers said they did not think the blasts were linked to militants. The airport said there was only a minor impact on its operations on Monday.
"Our understanding is that there is no nexus to terrorism," said Los Angeles Police Detective Gus Villanueva.
Officers also found two devices on Monday night that had not gone off, he added.
The airport temporarily closed its Terminal 2 on Sunday night after a report a bottle filled with dry ice had exploded in a staff bathroom.
In May, a similar device went off at Disneyland, forcing the evacuation of part of the park in Anaheim, California.