The ferry M/V Walla Walla will be out of service indefinitely after one of the vessel’s drive motors failed and left parts of the 188-car ferry melted and charred.

Washington State Ferries said the ferry was at Bainbridge Island for routine maintenance at the time of the incident on Sunday, Nov.v 4.

WSF said the ferry will be out of service for at least the next few months while it is being repaired.

Officials said the drive motor that was damaged is one of four motors that turn the propellers.

An internal investigation is underway, and ferry officials said an early examination indicates that there was no explosion.

“This is a serious incident and we’re going to do a very thorough and detailed investigation into what happened,” said David Moseley, WSDOT assistant secretary, ferries division. “We hope to return the vessel to service as soon as possible.”

The investigation will be conducted by a third party contractor, Cadick Corporation.

Results of the investigation are expected within two to three weeks.

Ferry officials also said they are working with the engine manufacturer to see if a spare drive motor can be used on the vessel.