As officials urged people to stay indoors for their safety, part of the search played out on live television Thursday night as officials executed several search warrants in the neighboring town of Bowdoin where Card lived.
Law enforcement surrounded the rural home for more than two hours, with an FBI agent issuing orders over a bullhorn to "come out with your hands up," but apparently nobody was inside.
Police did not know if Card was inside when the operation began and the amplified messages were "standard search warrant announcements," a Maine Department of Public Safety spokesperson said, adding that officials were "doing their due diligence" in tracking down leads.
The town of Lewiston, a former textile hub of 38,000 people, and neighbouring communities were largely shut down on Thursday to enable hundreds of officers to conduct their search.
The city on the banks of the Androscoggin River went quiet, with almost no cars on the roads, just a few people outside, and many downtown businesses closed. Rifle-toting security agents in bulletproof vests guarded the hospital where many of the shooting victims were taken.
Police circulated photographs of a bearded man in a brown hooded sweatshirt and jeans at one of the crime scenes armed with what appeared to be a semi-automatic rifle.
On the night of the shootings, Card's trail led to Lisbon, about 7 miles (11 km) to the southeast, where Maine State Police found a white SUV they believe Card used to get away and parked at a boat launch on the river. Public records showed he has three watercraft registrations: two Sea-Doos and a Bayliner.
The bloodshed rattled towns throughout Androscoggin County that were under shelter-in-place orders as they joined the growing list of US communities to suffer from a gun massacre.
"It's a small town. You get to know everybody," said Ken Spalding of Lisbon. "But I had told my wife a couple of years ago, 'It's not if, my dear. It's when.'"
The number of US shootings in which four or more people are shot is projected to reach 679 in 2023, up from 647 in 2022, according to data from the Gun Violence Archive.
The 18 fatalities are close to the annual number of homicides that normally occur in Maine, which has fluctuated between 16 and 29 since 2012, according to Maine State Police.
The victims included Bill Young and his 14-year-old son Aaron who were shot and killed at the Just-In-Time Recreation bowling alley, Bill's brother Rob Young told Reuters.
Also among the dead was Bryan MacFarlane, 40, who was part of a group in the deaf community participating in a cornhole tournament at Schemengees Bar & Grille when he was killed, his sister Keri Brooks told CNN.
Guns are lightly regulated in Maine, where about half of all adults live in a household with a gun, according to a 2020 study by RAND Corporation. Maine does not require a permit to buy or carry a gun, and it does not have so-called "red flag" laws seen in some other states that allow law enforcement to temporarily disarm people deemed to be dangerous.
US Representative Jared Golden, a Democrat from Lewiston, told reporters he has reversed his opposition to an assault weapons ban as a result of the tragedy.
"I now call on the United States Congress to ban assault rifles, like the one used by the perpetrator of this mass killing my hometown," Golden told a news conference.
But Congress has been mostly unable to pass gun control, even after previous tragedies such as the 2012 massacre at Sandy Hook Elementary School in Newtown, Connecticut, where 20 first-graders and six adults were gunned down.
