Safety investigators to probe whether dirty fuel contributed to Francis Scott Key Bridge collapse

A safety investigation into the Francis Scott Key Bridge collapse in Baltimore, Maryland, will include whether contaminated fuel was a factor in a cargo ship losing power and crashing into the bridge.

The lights on the Dali began to flicker about an hour into the ship's trip early Tuesday. A harbor pilot and assistant reported power issues and a loss of propulsion prior to the collision, according to a Coast Guard briefing report.

"The vessel went dead, no steering power and no electronics," an officer aboard the ship said Tuesday. "One of the engines coughed and then stopped. The smell of burned fuel was everywhere in the engine room and it was pitch black."

The ship did not have enough time to drop anchors to stop drifting, according to the officer, and crew members issued a mayday call before the crash happened.

Blackouts at sea are uncommon, but they do happen and have long been viewed as a major accident risk for ships on the water.

One cause of ship blackouts is contaminated fuel that can create problems with its main power generators, said Fotis Pagoulatos, a naval architect. He said a complete blackout could result in a ship losing propulsion and that smaller generators can kick in, but they are unable to carry all the functions of the main ones and take time to start.