The bus was only eight years old and had no previous problems.

Passengers aboard a bus headed from Minneapolis to Missoula, Mont., escaped unharmed when the bus caught fire in northwestern North Dakota.

The flames engulfed the Jefferson Lines bus near Williston about 8:30 p.m. Sunday. The 20 people onboard got off safely, although the bus likely is destroyed, company Marketing Director Kevin Pursey told The Associated Press on Monday. There was no immediate word on what caused the fire.

The bus was only eight years old and had no previous problems. All buses also go through a pre-trip inspection, Pursey said.

"We talked to the maintenance person today, and they looked at everything prior to it going out" of Minneapolis," he said. "It will be interesting to find out what the cause of it was."

Pursey said passengers had plenty of time to exit the burning bus safely.

"It's not something that's a made-for-TV type situation," he said.

Passenger Angel Ogden, of Missoula, told KECI-TV that some of the passengers lost luggage and other valuables in the fire, but Pursey said he thinks that all of the luggage was salvaged.

Another Jefferson Lines bus that normally travels Interstate 94 across southern North Dakota was being rerouted to Williston on Monday to pick up the stranded passengers.