One of the convicted killers who escaped from a maximum-security prison in upstate New York earlier this month was shot and killed by federal law enforcement officers Friday afternoon near a cabin a few miles south of the Canadian border, Gov. Andrew Cuomo (D) announced at an evening news conference.

U.S. Customs and Border Protection agents fatally shot Richard Matt on the 21st day of an intensive manhunt that began June 6, when officials at Clinton Correctional Facility discovered that Matt and David Sweat were missing.

Sweat remained at large, and Cuomo said “we don’t have anything to confirm where Mr. Sweat is at this time.”

Speaking at an evening news conference in Malone, N.Y., about 10 miles south of the international border and roughly 40 miles from the Dannemora prison where the men had been held, Cuomo said state police responded Friday afternoon to a call from a civilian who said somebody shot at the camping trailer he was towing.

Their investigation led to a cabin, where police detected the smell of gunpowder, the governor said. State Police Superintendent Joseph A. D’Amico said agents believed the cabin had been recently occupied, and that whoever had been inside it fled through the backdoor.

Search teams heard what they believed to be human coughs, D’Amico said, and a Customs and Border Protection tactical team helicoptered in, approached the site and encountered Matt, D’Amico said.

Matt was armed with a 20-gauge shotgun, D’Amico said, and refused to surrender.

At that point, Cuomo said. “Mr. Matt was shot and killed.”

“You never want to see anyone lose their life,” the governor said. “But I would remind people that Mr. Matt was an escaped murderer from a state prison; he killed two people, who we know about.”

Cuomo added that Sweat, a convicted cop killer, “is also dangerous.”

There was no actual sighting of Sweat at the site, D’Amico said. But, he added, there was “no indication that Sweat wasn’t accompanying Matt at the time.”

Police handout composite image showing David Sweat (L) and Richard Matt (R). (New York State Police via EPA)

As night fell, the Buffalo News reported, “a furious manhunt was underway for Sweat.”

According to the newspaper:

Giant flood lights were erected and convoys of State Police vehicles were seen speeding through the back dirt roads of the towns of Malone and Bellmont in clouds of dust, about 40 miles west of Clinton Correctional Facility in Dannemora, from which the two men escaped.

Law enforcement officers, standing just feet away from each other, slowly and methodically pushed through the woods, trying to flush Sweat out.

They were keenly aware that Sweat, now 35, killed a law enforcement officer before. He was doing a life sentence for killing a Broome County sheriff’s deputy in 2002 when he escaped with Matt.

Officials say Sweat and Matt, 49, used tools to break out of the maximum-security facility in northeastern New York either the night of June 5 or early morning on June 6; a civilian prison worker, Joyce Mitchell, and a correctional officer, Gene Palmer, have been arrested and charged with aiding their escape.

According to authorities, the men drilled through the prison’s steel walls and pipes, then crawled to their freedom through tunnels, popping out of a manhole in a nearby neighborhood. They left behind decoy dummies, as well as a note taunting prison officials.

As of Friday, according to the New York State Police, more than 1,100 federal, state and local law enforcement members were involved in the manhunt.

This post has been updated.