The United States Department of Justice has sued the Singapore-based owner and operator of a cargo tanker that slammed into the Francis Scott Key Bridge in Baltimore earlier this year.

The lawsuit filed on Wednesday seeks $100m from Grace Ocean Private and Synergy Marine Private, the owner and operator of the vessel, which collided with the bridge in March following a power failure. The impact caused the bridge to collapse, killing six workers on the structure and blocking a major US port.

“With this civil claim, the Justice Department is working to ensure that the costs of clearing the channel and reopening the Port of Baltimore are borne by the companies that caused the crash, not by the American taxpayer,” US Attorney General Merrick Garland said in a statement.

“The Justice Department is committed to ensuring accountability for those responsible for the destruction of the Francis Scott Key Bridge,” he added.

Meanwhile, Principal Deputy Associate Attorney General Benjamin Mizer said the collision was directly related to the companies’ negligence.

In a statement, he said the owner and operator of the 300-meter (1,000 foot) M/V Dali tanker, were “well aware of vibration issues on the vessel that could cause a power outage”.

“But instead of taking necessary precautions, they did the opposite,” he said.

“Out of negligence, mismanagement, and, at times, a desire to cut costs, they configured the ship’s electrical and mechanical systems in a way that prevented those systems from being able to quickly restore propulsion and steering after a power outage,” Mizer said.

He further described a cascading set of failures that led to disaster.

Grace Ocean and Synergy Marine had filed a legal action earlier this year seeking to limit their liability to $44m. The deadline to challenge that cap is September 24.

The lawsuit filed on Wednesday focuses specifically on costs related to the emergency response, clearing debris and reopening the Baltimore Harbor.

It does not relate to costs of rebuilding the bridge, which have been put at between $1.7bn and $1.9bn.

Families sue

The government’s legal action comes just a day after families of the victims who died on the bridge announced their own plans to launch legal action against the owner and operator.

All six of the victims were immigrants working an early morning shift on the bridge at the time of the collision. Their bodies were later recovered by salvage divers.

Maria del Carmen Castellon, whose husband Miguel Luna was killed, appealed for justice at a news conference on Wednesday.

“That day, a wound was opened in my heart that will never heal, something I would not wish on anyone,” Castellon said in Spanish, speaking through a translator.

Several local officials and businesses have also sued Grace Ocean and Synergy Marine, and more lawsuits are expected.