MALONE, N.Y. -- One of two convicted murderers who staged a brazen escape from an upstate maximum-security prison three weeks ago was shot and killed by a Border Patrol agent in a wooded area about 30 miles from the prison on Friday, and the other is on the run, authorities said.

Authorities tracked down Richard Matt after a person towing a camper reported that there was a bullet hole through the back of it, Gov. Andrew Cuomo and state police said at a news conference. David Sweat is still missing, and authorities are hunting for him.

The shooting of the camper led officers to a cabin Friday afternoon, where they discovered the smell of gunpowder, said Joseph D'Amico, superintendent of New York State Police. There was an indication that someone had recently been there and fled out the back door, he said.

While searching the property, officers heard coughs and tactical teams came upon Matt in the woods.

"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.

A 20-gauge shotgun was recovered from Matt, who did not fire his weapon, D'Amico said.

Authorities say it isn't clear if Matt and Sweat were together at the time of the shooting. Sweat hasn't been spotted, Cuomo said.

The pair escaped early June 6 from the prison in Dannemora, near the Canadian border.

Police blocked off roads in the area as officers hunted for Sweat. The search area for him is centred on Titusville Mountain State Forest in Malone and spans 22 square miles, down from 75 square miles earlier this week, authorities said.

Mitch Johnson said one of his best friends checked on his hunting cabin in Malone on Friday afternoon and noticed a liquor bottle that hadn't been there the day before. Johnson said his friend, correction officer Bob Willett, told him he immediately alerted police, about an hour before Matt was fatally shot.

Authorities sent a team to the camp area, and Willett and police later heard a gunshot in the woods, Johnson said.

Officers then flooded the woods, and then Willett heard more shots, Johnson said.

"He heard: 'Pop pop pop pop pop pop pop,"' Johnson said.

State Police Maj. Charles Guess said earlier Friday that the search area had shifted slightly northwest to Malone after investigators found evidence left behind by the escapees. Items were found Thursday at a cabin and Friday morning in a field, both in Malone, he said.

Matt and Sweat used power tools to saw through a steel cell wall and several steel steam pipes, bashed a hole through a 2-foot-thick brick wall, squirmed through pipes and emerged from a manhole outside the prison.

Sweat was serving a sentence of life without parole in the killing of a sheriff's deputy in Broome County in 2002. Matt was serving 25 years to life for the killing and dismembering of his former boss. They were added to the U.S. Marshals Service's 15 Most Wanted fugitives list two weeks after getting away.

The search for the escapees was initially concentrated around the prison and a rural community where search dogs had caught the scent of both men. The search had since been expanded to neighbouring counties, and, while authorities said there was no evidence the men had gotten out of the general area, they conceded they could have been almost anywhere.

Vermont authorities became involved in the search early on after investigators got a tip that the inmates had talked about going there.

A pair of prison workers has been charged in connection with the inmates' escape.

Prosecutors said Joyce Mitchell, a prison tailoring shop instructor who got close to the men while working with them, had agreed to be their getaway driver but backed out because she felt guilty for participating. Authorities also said Mitchell had discussed killing her husband, Lyle Mitchell, as part of the plot.

Joyce Mitchell pleaded not guilty June 15 to charges including felony promoting prison contraband, which authorities said included hacksaw blades and chisels.

Authorities said the men had filled their beds in their adjacent cells with clothes to make it appear they were sleeping when guards made overnight rounds. On a cut steam pipe, the prisoners left a taunting note containing a crude caricature of an Asian face and the words "Have a nice day."

Clinton County District Attorney Andrew Wylie said the inmates apparently used tools stored by prison contractors, taking care to return them to their toolboxes after each night's work.

On June 24, authorities charged Clinton correction officer Gene Palmer with promoting prison contraband, tampering with physical evidence and official misconduct. Officials said he gave the two prisoners the frozen hamburger meat Joyce Mitchell had used to hide the tools she smuggled to Sweat and Matt. Palmer's attorney said he had no knowledge that the meat contained hacksaw blades, a bit and a screwdriver.