The bearded man wore a brown top, blue pants and brown shoes, and police asked for anyone with information on his identity to contact them immediately. / Photo: AFP

A massive manhunt was under way Thursday for a gunman who a local official said killed at least 22 people and wounded dozens more in mass shootings in the US state of Maine, the deadliest such incident this year.

Police said Robert Card - seen in CCTV footage pointing a semi-automatic weapon with an extended clip as he walked into a bowling alley in the city of Lewiston - "should be considered armed and dangerous."

Card is a certified firearms instructor and a member of the US Army Reserve, CNN reported, citing law enforcement sources.

Lewiston city councillor Robert McCarthy told CNN that law enforcement had "confirmed 22 dead, many, many more injured", with local media reporting shootings had occurred at multiple locations.

Locked down

Swathes of the city of Lewiston were locked down, with businesses urged to shutter and people ordered to shelter in place, as the scourge of horrifying gun violence once again ripped through an American community.

Maine public safety official Mike Sauschuck said he was not prepared to give a death toll, calling it "a very fluid situation."

He told reporters police were flooding the streets as they sought the gunman.

"We have literally hundreds of police officers working around the state of Maine to investigate this case, to locate Mr. Card," he told reporters.

Rescue vehicles rushed in from around central Maine to tend to the wounded, McCarthy said, and the two Lewiston hospitals "have called in every off-duty staff member that they could to deal with this."

Biden's state dinner

President Joe Biden made calls - stepping away from a state dinner honoring Australia's prime minister - to Maine's governor, its two senators and a local congressman to offer federal support, the White House said.

Police and rescuers reportedly arrived at the Sparetime Recreation bowling alley at approximately 7:15 pm local time (00:15 Thursday GMT) in response to an active shooter, and thereafter received reports of another shooting at the Schemengees Bar & Grille, according to the Sun Journal local newspaper.

Police issued a number of photographs of 40-year-old Card at the bowling alley, where he appears calm and composed as he moves through the doorway with his rifle raised.

"Please contact law enforcement if you are aware of his whereabouts," they said.

Stay off streets

Sauschuck said officers had located a "vehicle of interest" they had been looking for -- a white sport-utility vehicle (SUV) -- in Lisbon, a town around eight miles (12 kilometers) from Lewiston, where residents had also been warned to stay off the streets.

Card was not in the vehicle, reports said.

Law enforcement "are investigating two active shooter events," the Androscoggin County Sheriff's Department wrote on Facebook.

"We are encouraging all businesses to lock down and or close while we investigate. The suspect is still at large."

Maine Governor Janet Mills said she was "aware of and have been briefed on the active shooter situation in Lewiston."

CNN reported that at least 50 to 60 people were wounded in the incidents, citing multiple law enforcement sources, but said it was unclear how many of the injuries were the result of gunfire.

It was unclear if initial reports of shots being fired at a third site, a Walmart distribution center, were accurate.

Gun violence is alarmingly common in the United States, a country where there are more guns than people and where attempts to clamp down on their spread are always met with stiff resistance.

Lewiston is the second most populous city in Maine located some 30 miles (50 kilometers) north of the largest city, Portland.

AFP