A 40-year-old firearms instructor who had been named a suspect in Wednesday’s mass shooting at two businesses in Lewiston, Maine, was found dead Friday, four senior law enforcement officials told NBC News.

No additional details were immediately available. A news conference was scheduled for 10 p.m.

Eighteen people were killed in the shootings, when Robert Card allegedly opened fire at Schemengees Bar and Grille and the Just-In-Time Recreation bowling alley Wednesday evening in Lewiston, a city of around 37,000.

Follow along for live coverage

The development comes after a massive manhunt described by Maine’s public safety commissioner as a “full court press.” More than 350 law enforcement personnel were involved in the search, state police said.

Residents of Lewiston, as well as several surrounding towns, were told to shelter in place after the shootings. The order was listed Friday evening. Lewiston, the state’s second-largest city, resembled a ghost town with many businesses closed.

The gunfire, which occurred around 7 p.m. Wednesday at two businesses around 4 miles apart, is the deadliest mass shooting in Maine history. Photos released by law enforcement showed a man in a hooded sweatshirt walking with a black rifle with what appeared to be a scope.

A motive in the killings was unknown as the manhunt continued.

A member of Card’s family said his mental health had deteriorated quickly, and that he began to hear voices.

Card was a longtime Army reservist. His unit commanders sent him to receive psychiatric treatment this summer, and he spent about two weeks undergoing inpatient psychiatric treatment, two senior law enforcement officials said.

An arrest warrant had been issued for Card for eight counts of murder, Maine State Police said Thursday morning. The eight counts were based on the initial identification of eight of the 18 dead, and the number of counts will probably go up, state police Col. William Ross.

All 18 of the dead have been identified, and their names were read by Maine Department of Public Safety Commissioner Mike Sauschuck during a news conference Friday.

After the shootings Wednesday, Card’s Subaru was sought by police and was found later that night by a boat launch in Lisbon, a town around 7 miles southeast of Lewiston, officials have said.

On Thursday, police executed search warrants in Bowdoin, the small town around 12 miles east of Lewiston where Card lived.

The shootings shocked Mainers and people across the nation.

President Joe Biden said the United States was mourning “yet another senseless and tragic mass shooting.” Sen. Susan Collins, R-Maine, called it a “heinous attack.”

At the Just-In-Time Recreation bowling alley, it was youth night when the gunman entered and opened fire.

“They’re just innocent people out for a night of bowling,” said Kim McConville, whose cousin and his 14-year-old son were killed at the bowling alley. “This was a children’s event. Who expects a shooter to go into a children’s event?”

Lewiston and the adjacent city of Auburn, just across the Androscoggin River, has a population of around 65,000 people.