A US Army reservist is wanted for murder after 18 people were killed and 13 others injured in a mass shooting in Lewiston, Maine.
Police said they issued an arrest warrant for Robert Card on eight counts of murder.
“It’s eight counts because 10 people have not been identified,” Maine State Police Col. William Ross said.
The suspect is at large and is considered “armed and dangerous”, Col. Ross said.
The shooting began at a bowling alley in the small town of Lewiston just before 19:00 local time (23:00 GMT), the police colonel said. One woman and six men were killed there.
Within about 10 minutes, gunfire was reported at a nearby restaurant, Schemengees Bar & Grille, where eight more men were fatally shot.
Sixteen injured people were initially transferred to local hospitals, three of whom later died.
On Thursday night local law enforcement and FBI agents surrounded Mr Card’s home, around 20 minute drive from Lewiston where the shooting happened.
Police yelled through a megaphone telling the suspect to come out of the house “with your hands up”.
But it is unclear what prompted the search, and a spokesperson for the Maine Department of Public Safety said officers were “simply doing their due diligence by tracking down every lead in an effort to locate and apprehend Card”.
Meanwhile, in Lewiston and three nearby towns remain under a shelter in place notice. Schools as well as local stores and shops have closed and many will remain so on Friday.
Beyond a few dog walkers, most people appeared to have stayed at home on Thursday. Police have been posted on the streets.
The only bustles of activity are near the two shooting sites and the Central Maine Medical Center.
Dr John Alexander, the chief medical officer there, called the attack “unprecedented” for the small city. He said about 50 providers, nurses, respiratory therapists and surgeons answered the call to help treat the victims.
Maine State Police said the suspect had recently reported mental health issues, including “hearing voices and threats to shoot up a military installation in southern Maine”.
He had reportedly been admitted to a mental health treatment facility in the summer, after behaving erratically during training at the US Military Academy.
Police denied earlier reports that he was a firearms instructor, saying there was “no indication he attended advanced weaponry courses”.
Maine’s Governor Janet Mills, a former Lewiston resident, called it a “dark day” for her state and pledged “to seek full justice for the victims and their families”.
The FBI and other federal US law enforcement agencies are aiding local and state police in the manhunt. Neighbouring states are also providing resources and remaining vigilant, as the suspect could have travelled across state lines.
President Joe Biden ordered flags at the White House and other federal buildings to be lowered to half-mast as a mark of respect for those who died.
He also called on Republican lawmakers in Congress to pass gun safety legislation.
“This is the very least we owe every American who will now bear the scars – physical and mental – of this latest attack,” he said.
Speaking at a news conference on Thursday, Maine Senator Susan Collins called for a ban on high-capacity magazines.
“Our hearts are heavy with grief,” she told reporters. “This heinous attack, which has robbed the lives of at least 18 Mainers and injured so many more is the worst mass shooting that the state of Maine has ever experienced and could ever imagine.”