The city of Washington, D.C., sued the right-wing groups the Proud Boys and the Oath Keepers on Tuesday, seeking to collect on the financial costs of the deadly Jan. 6 attack on the US Capitol and its aftermath.

The suit aims to hold accountable two groups that prosecutors say played a leading role in an assault by thousands of supporters of then-President Donald Trump that aimed to prevent Congress from certifying Democrat Joe Biden‘s election victory.

District of Columbia Attorney General Karl Racine told reporters the defendants had caused physical and financial harm to Washington and its residents, adding that the city will seek “severe” financial penalties against the defendants.

“Our intent … is to hold these violent mobsters and these violent hate groups accountable and to get every penny of damage we can,” he said at a news conference.

The lawsuit seeks to recover the costs of deploying roughly 1,100 city police officers to bolster other police forces who defended the Capitol against the attack, which it says amounts to millions of dollars.