Thousands of anxious small-town Maine residents began a second day under lockdown Friday as police waging a sprawling manhunt struggled to find a US Army reservist accused of killing 18 people in America's deadliest mass shooting this year.

Dozens of law enforcement agents surrounded the family home of the suspect, Robert Card, 40, but by mid-evening agents left the property in Bowdoin, near Lewiston, Maine, to hunt for him elsewhere.

A wide area around Lewiston remained locked down Friday, more than 24 hours after Card allegedly went on a rampage in which 13 people were also wounded.

People in Lewiston were on edge, buzzing with talk of Card and the massacre.

"Uneasy," said resident Jeremy Hiltz, when asked how he felt. "It's a small community . When something like this happens, everybody knows somebody" affected."

Authorities erected roadblocks, ordered schools and businesses closed, and told residents to stay indoors.

Governor Janet Mills said the suspect was considered armed and dangerous.

Card was seen in surveillance footage pointing a semi-automatic rifle as he walked into the Just-in-Time bowling alley on Wednesday.

In early evening, law enforcement agents surrounded the Card family home in Bowdoin, bringing in armored vehicles, and sending up drones and a helicopter.

State police warned "please come outside" and "we don't want anyone to get hurt" over a loudspeaker near the home, but later said the warnings were routine and not confirmation that Card was inside.

One longtime neighbor, Dave Letarte, said news of the shooting "floored me."

"I would have never expected that from him," he told AFP of Card.

Joseph Walker, a manager at the Schemengees Bar & Grille, was among those killed Wednesday night, his father, Leroy Walker, told NBC News.

Walker said his family was "suffering and dying in a nightmare we don't understand."

"We were up all night. We didn't know where to go, who to turn to," he said.

Terror at bowling alley

One survivor told television reporters that he was 15 feet (5 meters) from the gunman when he opened fire at the bowling alley. He thought at first it was a balloon popping.

"And as soon as I turned and saw it was not a balloon and he was holding a weapon, I just booked it down the lane and I slid basically into where the pins are and climbed up into the machine and was on top of the machines for about 10 minutes until the cops got there," he said.

Card is a member of the US Army Reserve, but had not been deployed in any combat zone. US media reported that he had recently been sent for psychiatric treatment after he said he was hearing voices.

Hundreds of police in military style camouflage gear, as well as FBI agents, flooded the search zone in what Lewiston police chief David St. Pierre called "an all-hands-on-deck approach."

Republicans oppose new laws

This latest shooting is one of the deadliest in the United States since 2017, when a gunman opened fire on a crowded music festival in Las Vegas, killing 60 people.

Mass shootings are common in the United States, a country with more privately owned guns than people, and strong political opposition to even minor restrictions on access.

The country has recorded at least 565 mass shootings this year, according to the Gun Violence Archive, a nongovernmental organization that defines a mass shooting as four or more people wounded or killed.

President Joe Biden called Maine's governor to offer federal support, and ordered flags to be lowered to half-staff at the White House and all government buildings.

Biden added that the gun violence that plagues the United States "is not normal, and we cannot accept it," urging lawmakers to pass a bill banning assault weapons and high-capacity magazines.

A Maine Democrat who holds a seat in the US House of Representatives, Jared Golden, flipped on this ban, saying that after the shooting in his state his previous opposition to such a restriction, which is supported by most in his party, was a mistake.

"I have opposed efforts to ban deadly weapons of war, like the assault rifle used to carry out this crime," Golden said Thursday.

"The time has now come for me to take responsibility for this failure," he added.

But in a reminder that Congress will not be considering stronger gun ownership laws anytime soon, the newly installed Republican speaker of the House of Representatives, Mike Johnson, told Fox News that the reason for so many mass shootings in the United States "is the human heart, not guns."