After another Metrobus vehicle of a model with an already troubled service history caught fire Tuesday morning in Maryland, the Washington Metropolitan Area Transit Authority announced it is suspending its entire stock of that type of bus from service pending an investigation.

The Orion VI bus that lit up about 6 a.m. on Route 50 in Prince George’s County was the second of that model to catch fire in less than a week, according to a WMATA press release. Of Metrobus’ fleet of nearly 1,500 buses, 94 Orion VI vehicles will be removed from the streets. Only a mechanic driving the bus was on board this morning, Metro said.

“Safety is our highest priority, and this is a prudent step until we fully understand the cause,” Metro General Manager Richard Sarles said in the press release about the removal of the buses, which the transit authority received in 2000.

But the recent fires are hardly the first problem Metrobus has had with the Orion VI, which is produced by Ontario-based Orion International and used in transit systems throughout the United States and Canada. In September 2010, Metro suspended their use after a faulty hydraulic pump sparked a fire on a bus near Springfield, Va., and a 2007 fire aboard an Orion VI bus on K Street NW was blamed on its braking and air-drying systems.

Metro did not give a timetable on how long this new investigation will take, though Sarles said the agency would “do everything possible to minimize customer impact while these buses are out of service.”

For a view of the bus’ charred remains, check out NBC4.