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Richard Matt, one of the two killers who escaped from an upstate New York prison three weeks ago, was shot and killed by a U.S. Customs and Border patrol tactical team during the manhunt Friday, police said.

The other escaped inmate, David Sweat, remains on the loose. Police believe Sweat could be nearby and continued to search for him Friday night.

Matt was shot dead at around 3:45 p.m. in a wooded area south of the town of Malone by a member of a U.S. Customs and Border patrol tactical team, New York State Police Superintendent Joseph D'Amico told reporters Friday night.

"They verbally challenged him, told him to put up his hands, and at that time he was shot when he didn’t comply," D'Amico said.

After Matt was shot, a 20-gauge shotgun was found near his body. D'Amico said. He said Matt did not fire the weapon before he was killed.

Matt and Sweat have been the targets of a massive manhunt after they used power tools to saw through their prison cells and escape from Clinton Correctional Facility in Dannemora, about 30 miles east of Malone, on June 6.

Law enforcement was searching in the area near the Canadian border after a series of burglarized cabins indicated one or both inmates might be headed toward Canada.

At around 1:50 p.m. a driver reported that his towed camper had been shot at, and searchers found a cabin that smelled of gunpowder and appeared to have been recently occupied near the site of that incident, D’Amico said. It appeared that whoever was inside the cabin fled out a rear door, he said.

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Searchers heard a noise, D'Amico said.

"As we were doing the ground search in the area, there was movement detected by officers on the ground, what they believed to be coughs, so they knew they were dealing with humans as opposed to wildlife,” D’Amico said.

The U.S. Customs and Border patrol tactical team then found and killed Matt, D'Amico said.

Video shot by a bystander captured a swarm of law enforcement vehicles, and an officer could be heard saying, "We have one guy down."

The shotgun is thought to have been stolen from a hunting cabin, which authorities had already connected Matt to. It is similar to a 20-gauge shotgun that was missing from the cabin, D'Amico said.

"We’ve always gone under the assumption that these men were armed," D'Amico said. Both he and Gov. Andrew Cuomo warned residents to remain vigilant and report anything out of the ordinary to police while Sweat was still on the run.

While Sweat could be nearby, Cuomo and D’Amico said they can’t be certain because investigators haven’t found definitive evidence linking Sweat to Malone on Friday. D’Amico said that evidence had been recovered that indicated the inmates "were together at some point after the escape."

"We are going to continue the same tactics we’ve used over the past three weeks, which is to search 24 hours a day until we find them,” D’Amico said.

A prison seamstress, Joyce Mitchell, has been charged with helping the two escape. Authorities have said she was romanced by Matt and was originally supposed to be the getaway driver. They have said she smuggled tools to the men inside packages of raw meat.

She is accused of bringing hacksaw blades, chisels, a punch and a screwdriver bit into the prison five weeks before the escape. Clinton County District Attorney Andrew Wylie said she also provided glasses with lights attached, presumably to be used in the tunnels.

Wylie said Mitchell planned to meet the men at around midnight on the night of the escape and pick them up, but got cold feet.

This week authorities charged a second prison worker, Gene Palmer, and said he delivered the packages. Palmer's attorney said the prison guard was unaware of the escape plot, and had no idea the packages contained contraband.

Matt, 49, was sentenced to 25 years to life in 2008 for killing and dismembering a businessman whose torso was discovered in the Niagara River by a fisherman.

Matt fled to Mexico and was arrested for stabbing an American to death outside a bar in a robbery attempt. He was returned to the United States to face trial in the businessman's killing.

He escaped from prison once before, in 1986, and at his trial he was considered so dangerous that police snipers were posted on the courthouse roof.

Sweat, 35, pleaded guilty to first-degree murder and was sentenced to life without parole in the shooting death of Kevin Tarsia, a sheriff's deputy in Broome County, New York, on July 4, 2002.