The Army should investigate the October mass shooting by one of its reservists that killed 18 people in Lewiston – the worst in Maine’s history, the state’s congressional delegation says.

Authorities said Robert Card shot 18 people in a bowling alley and a restaurant in Lewiston on Oct. 25 and was found dead – with a gunshot wound he inflicted on himself – two days later. Reports said the 40-year-old Card had been in a mental hospital for two weeks and was collecting weapons at the same time.

The Maine delegation asked the Department of the Army Inspector General to investigate after meeting with families of the victims in Washington.

The delegation said on Friday that Army officials told them there would be an administrative investigation of what happened before Card’s death. The members said in a statement that they wanted another, independent, simultaneous investigation of the shootings that was more thorough than the administrative one.

“This tragedy needs a wider, independent inquiry,” the delegation members said in the statement. “We have to fully understand what happened – and what could have changed that might have stopped the Lewiston shooting – at the local, state, and federal levels. We also have to assure the American people that the investigation is complete and fair.

The Army did not comment right away when asked on Saturday.

The delegation asked for an independent investigation the day after they met with a survivor and relatives of the victims of the shootings. The families went to Capitol Hill to demand that the Department of the Army Inspector General explain how Card could have guns and do the shootings.

Card’s military weapons were taken away after he came out of the mental hospital. Sen. Susan Collins, a Republican and the most senior member of the delegation, said New York’s red flag law or Maine’s yellow flag law could have been used to take away Card’s weapons after the Army restricted him. Collins, independent Sen. Angus King and Democratic Reps. Chellie Pingree and Jared Golden asked for the investigation on Friday.

The Lewiston families said in a statement on Friday night that they were grateful for the quick action from the lawmakers after meeting them. They said it was important to find out “the facts about what happened before the October 25 mass shooting and any problems or failures” that let Card do the shootings.

“The joint letter says that even though the Army is doing an administrative investigation, an inspector general investigation can be done at the same time,” the statement said.