The large ship that hit the Francis Scott Key Bridge in the Baltimore Harbor had lost power twice the day before bringing down the bridge, a preliminary National Transportation Safety Board report found.
The report found the Dali experienced a power outage during maintenance about 10 hours before it left the Port of Baltimore.
The report stated, "A crewmember mistakenly closed an inline engine exhaust damper."
The closure reportedly blocked the engine's cylinder exhaust gases from traveling up its stack and out of the vessel. That caused the engine to stall, investigators say.
The ship then experienced a second blackout shortly before it hit the bridge.
Six construction workers on the bridge died in the collapse. The last of the victims' bodies was recovered last week, the Associated Press reported.
The Dali was loaded with shipping containers and headed from Baltimore to Sri Lanka.
Salvage crews performed a controlled demolition on Monday to blow up a section of the Key Bridge still on the port side of the bow of the Dali.
The ship is expected to be refloated and moved back to the Port of Baltimore in the coming days.
Debris and wreckage removal is ongoing in support of a top priority to safely and efficiently open the Fort McHenry Channel.
Members of the NTSB and other federal agencies are scheduled to testify in front of a Congressional committee about the response and investigation on Wednesday.
The FBI has launched a criminal investigation into the circumstances leading up to the crash.
