It sounds like a driver’s dream – and a security guard’s nightmare: more than half a million dollars in cash spilling out onto a busy highway.

A total of $510,000 dollars accidentally spilled out of a door left open on a Brinks armored truck as it drove down Route 3 in East Rutherford, New Jersey Thursday morning, causing stunned drivers to slam on the brakes – and jump out of their cars in a mad-dash to pick up the cash.

Traffic came to a standstill as drivers stopped in the middle of the highway and rushed out to grab 20-dollar bills scattered across the pavement.

While some drivers assisted the Brinks driver collect the lost money rather than pocket the cash, less than half was retrieved.

On Friday, Brinks reported that just $205,375 dollars had been collected in the incident.

Police said that two bags, carrying $140,000 and $370,000 in cash had fallen out of the vehicle from a door accidently left open. As the truck was driving down Route 3, the two bags slipped out, and spilled their contents onto the road.

Authorities in East Rutherford warned drivers who pocketed the cash that they were not permitted to keep the money, and announced plans to investigate those who do not return the money.

"It's theft of mislaid property," said East Rutherford Detective Lieutenant Mike Gianscaspro.

By Saturday, however, the East Rutherford Police Department had reported that just $11,090 of the nearly $300,000 in missing bills were returned. The $11,090 returned to Brinks had been brought in by just five individuals.

As of Saturday, police said there was still $293,535 missing.

“2 bags of $ fell out of armored truck ($140,000 & $370,000) employees w/ assistance of motorists recovered & secured $205,375 from roadway. 5 individuals returned a total of $11,090.00 w/ $293,535.00 still outstanding,” police tweeted Saturday.