OLYMPIA, Wash. - A Seattle tour company involved in a deadly crash in September can resume operating a limited fleet of amphibious vehicles but must gain approval for a safety plan by the end of next month or risk being put out of business under a decision Monday by state regulators.

After a three-hour hearing, the three-member Washington Utilities and Transportation Commission approved a joint stipulation that allows the company to resume operations of its "Truck Duck" vehicles.

"Truck Duck" vehicles have a different manufacturer, chassis, and axle system from the "stretch duck" vehicle involved in the Sept. 24 accident in which five international college students were killed when the repurposed military "duck boat" swerved into an oncoming charter bus on the Aurora Bridge, a six-lane span with no median barrier.

The company's operations were suspended by the commission days after the accident.

"Our sole inquiry at this point is to determine whether an immediate danger to public safety still exists that the commission must prevent or avoid," commission Chairman David Danner said Monday. "We conclude that no immediate danger to public safety exists that requires continued suspension of the entirety of Ride the Ducks' certificate."

Stretch duck vehicles, like the one involved in the accident, are still barred from the road until the company demonstrates that those vehicles pose no threat to public safety, he said.

Ride the Ducks of Seattle owner Brian Tracey told the commission that he doesn't have a time frame on when the 10 vehicles could be on the road, saying that drivers will need to be retrained and that he wants to "make sure everything we're doing is perfectly buttoned down before we're up and running again."

Under the agreement, the company must submit a safety plan and have it approved by Jan. 29. If their plan is accepted, the company's safety rating will be upgraded from "unsatisfactory" to conditional, contingent on follow-up investigations.

If the company fails to provide an adequate plan, the vehicles will be put out of service and prohibited from operation.