In scenes reminiscent of a Hollywood movie, drivers on a Southern California freeway have scrambled to grab piles of dollar bills after bags of money fell out of an armoured truck.

The incident occurred shortly before 9.15am local time on Friday on Interstate 5 in Carlsbad as the truck was heading from San Diego to an office of the Federal Deposit Insurance Corporation, authorities said.

“One of the doors popped open and bags of cash fell out,” California Highway Patrol Sergeant Curtis Martin said.

Several bags broke open, spreading money – mainly $US1 and $US20 bills – all over the lanes and bringing the freeway to a chaotic halt, Martin said.

Video posted online showed some people laughing and leaping around with their hands full of wads of cash.

Two people were arrested at the scene, and Martin warned any others who are found to have taken the money could face criminal charges.

He noted there was plenty of video taken by bystanders at the scene and that the Highway Patrol and FBI were investigating.

Authorities did not immediately say how much money was lost.

However, at least a dozen people had returned cash they collected to the CHP by Friday afternoon, the San Diego Union-Tribune reported.

“People are bringing in a lot,” Martin said. “People got a lot of money.”

-AAP