Two electrical breaker failures were the cause of the Dali losing power just before it rammed into the Francis Scott Key Bridge in March.

The National Transportation Safety Board issued a preliminary update to its report on the incident on Monday.

“During the accident voyage, electrical breakers HR1 and LR1 unexpectedly opened when the vessel was three ship lengths from the Key Bridge, causing the first blackout (loss of electrical power) to all shipboard lighting and most equipment,” the report stated.

The preliminary information is the first update on the incident since the NTSB issued its initial report in mid-May. That investigation found that the ship, the Dali, lost power before hitting the bridge, but did not conclude why.

The NTSB is continuing its investigation. The FBI and U.S. Coast Guard are conducting parallel investigations.

The Dali left Baltimore on Monday for repairs in Norfolk, Virginia. It’s the first time the ship has left the area since the accident.

Some of the 23 crew members are still in Baltimore, while eight were able to head back to their home countries of India and Sri Lanka last week.

Baltimore is currently in the process of taking legal action against the company that owns the Dali, Grace Ocean Private for damages and economic impact.

At least one company and some of the families of the six construction workers that died on the bridge are also suing Grace Ocean Private.