A man suspected of fatally shooting 18 people and injuring 13 others in the United States earlier this week was found dead on Friday, reported AFP.

Robert Card, a 40-year-old Army reservist, died of a self-inflicted gunshot wound, said Maine public safety commissioner Mike Sauschuck.

“I am breathing a sigh of relief tonight knowing that Robert Card will not be a threat to anyone,” said Janet Mills, the governor of Maine.

Card allegedly went on a shooting rampage on Wednesday in a bowling alley and a bar-restaurant in the city of Lewinston. This was the 36th mass shooting case in the United States this year and the deadliest, according to the Associated Press.

Law enforcement officials said that a suicide note addressed to Card’s son, along with a cell phone, was found in his home on Thursday. They also found a gun in a vehicle abandoned by the suspect and were attempting to find out where it was acquired from.

Card’s relatives told investigators that he had recently spoken to them about hearing voices. He had also become more focused on the bowling alley and bar, they had said.

The New York Army National Guard said the Army Reserve’s 3rd Battalion, 304th Infantry Regiment became concerned about Card’s behaviour when they were training at the US Military Academy in New York. He was taken by the police for an evaluation in mid-July.

Commenting on the Lewingston shooting, United States President Joe Biden said on Friday that he would continue to do everything in his power to “end this gun violence epidemic”.

“Americans should not have to live like this,” he said. “I once again call on Republicans in Congress to fulfil their obligation to keep the American people safe.”