The Department of Justice is suing the owner and operator of the container ship Dali, saying negligence and dangerous cost-cutting decisions led to the ship ramming into -- and destroying -- Baltimore's Francis Scott Key Bridge in March.

The catastrophe killed six construction workers and shut down a busy port for months; it also obliterated a segment of Interstate 695 carried by the bridge.

"The ship's owner and manager ... sent an ill-prepared crew on an abjectly unseaworthy vessel to navigate the United States' waterways," the Justice Department alleges in a civil claim that was filed on Wednesday in a federal court in Maryland.

The government is suing two Singapore-based corporations, Grace Ocean Private Limited and Synergy Marine Private Limited, seeking more than $100 million in costs the U.S. incurred in responding to the disaster.

"The Justice Department is committed to ensuring accountability for those responsible for the destruction of the Francis Scott Key Bridge, which resulted in the tragic deaths of six people and disrupted our country's transportation and defense infrastructure," Attorney General Merrick B. Garland said in a news release.