LEWISTON, Maine (AP) Lawyers for 100 survivors and relatives of victims of the deadliest shooting in Maine history have begun the formal process of suing the U.S. Army for what they say was a failure to act to stop the reservist responsible for the crime, attorneys announced Tuesday.

The individual notices of claim say the Army failed to act despite being aware of the reservists mental health decline that led to his hospitalization and left him paranoid, delusional and expressing homicidal ideations including producing a hit list of those he wanted to attack.

It is difficult to conceive of a case in which Army personnel could have more warning signs and opportunities to intervene to prevent a service member from committing a mass shooting than what happened in the case of Army Reservist Robert Card, the lawyers wrote.

The notices of claim by four law firms, one of which worked with victims of the 2012 Sandy Hook , Connecticut, mass shooting, are a required step in suing the federal government. The Army will have six months to determine whether to respond, after which lawyers are poised to file a lawsuit. The Army said in a statement Tuesday that it does not comment on litigation.