Law enforcement agencies are searching for the suspect in a mass shooting that left at least 18 people dead and 13 injured Wednesday at a bowling alley and a bar in the town of Lewiston, Maine.

The suspect, Robert Card, remained at large Thursday and is considered armed and dangerous, Gov. Janet Mills told reporters at a press conference. Card should not be approached under any circumstances, Mills said.

The governor said the full weight of her administration is behind the search for Card and that the person responsible for the shootings will be held “accountable under the full force of state and federal law.”

Card, 40, is a trained firearms instructor and an Army reservist, according to a bulletin from the Maine Information and Analysis Center.

He was committed to a mental health facility in the summer after he “reported mental health issues to include hearing voices and threats to shoot up” a National Guard base in Maine, according to the bulletin. He was released from the facility after two weeks.

The search is a coordinated effort between federal, state, county and municipal law enforcement. Anyone with information about Card or the shootings should call (207) 213-9526 or (207) 509-9002, police said.

The rifle used by the suspect was purchased legally this year, two senior law enforcement officials briefed on the matter told NBC News.

State police have issued a shelter-in-place order for Lewiston and the neighboring towns of Lisbon and Bowdoin as law enforcement personnel search for Card. People should stay in their homes with the doors locked, police said.

The gunman opened fire at Just In Time Recreation bowling alley and Schemengees Bar & Grille, both in Lewiston, on Wednesday evening, leaving seven people dead at the bowling alley and eight people dead at the bar. Three more people were pronounced dead at the hospital. The two businesses are located about 12 minutes apart by car.

President Joe Biden has spoken individually with Mills, Sen. Angus King, I-Maine, Sen. Susan Collins, R-Maine, and Rep. Jared Golden, D-Maine, according to the White House. Biden has also offered federal support to state and local law enforcement.

“For countless Americans who have survived gun violence and been traumatized by it, a shooting such as this reopens deep and painful wounds,” Biden said in a statement Thursday.

“Far too many Americans have now had a family member killed or injured as a result of gun violence,” he added. “That is not normal, and we cannot accept it.”

Biden called on Republican lawmakers to work with Democrats to pass a bill banning assault weapons and high-capacity magazines, enact universal background checks, require the safe storage of guns, and end immunity for gunmakers.

This is a developing story. Please check back for updates.