Robert Card, a 40-year-old soldier in the U.S. Army Reserve, is suspected of gunning down 18 people in a small town in the northern state of Maine.
The shooting -- which targeted a bowling alley and a bar in Lewiston on Wednesday night -- is one of the deadliest since 2017, when a gunman opened fire on a crowded music festival in Las Vegas, killing 60 people.
Authorities have issued a warrant to arrest Card for murder, Colonel William Ross of the Maine State Police told a press conference Thursday, adding that he is considered "armed and dangerous" and warning people not to approach him.
The Lewiston police department released images of a bearded man dressed in a brown hoodie and blue cargo pants and armed with an assault rifle.
Card is a certified firearms instructor, according to multiple law enforcement sources.
The U.S. Army provided details on Card's military service, saying he enlisted in December 2002 and is a sergeant first class in the Army Reserve with "no combat deployments."
"The Army did not train SFC Card as a firearms instructor, nor did he serve in that capacity for the Army," a spokesman said in a statement.
Card is a Petroleum Supply Specialist, which entails supplying the Army "with the fuel it needs to maintain a state of readiness at all times," according to a U.S. military career website.
"You'll supervise and manage the reception, storage, and shipping of bulk or packaged petroleum-based products. You'll oversee its use, dispense it to various vehicles and aircraft, and make sure it is being transported and handled safely," it says.
According to ABC News, Card spent two weeks at a mental health facility earlier this year after allegedly threatening to carry out a shooting at a National Guard facility.
NBC News also referred to a threat to a National Guard installation, citing a law enforcement bulletin as saying Card "recently reported mental health issues to include hearing voices and threats to shoot up the National Guard Base" in Saco, Maine.
Officials at Thursday's press conference would not elaborate on the reports, however, saying they did not yet know the motive behind the killings.
Maine resident Liam Kent told NBC that he grew up near Card and his family, who he described as "gun fanatics."
"They for all intents and purposes are very much associated with right-wing militias. It's known in the town to stay away from them and to not approach them," Kent said.
