Updated at 3:40 p.m. ET

Authorities on a massive manhunt for a pair of convicted murderers, who made an extraordinary escape from a prison in upstate New York two weeks ago, have shifted the focus of their search to Allegany County near the Pennsylvania border after reports of a possible sighting of David Sweat and Richard Matt.

North Country Public Radio quotes state police as saying that a person spotted two men Saturday near railroad tracks that run along Route 20 at the town of Friendship. Authorities say they are searching there and along route I-86.

NCPR's Brian Mann reports:

"On Saturday, State Police issued a warning to community residents in that part of western New York, urging them to be vigilant." 'While this is an unconfirmed sighting, the State Police is asking residents who live in this area along the New York-Pennsylvania border to be on alert,' authorities said." 'If these men are spotted, please call 911 immediately. Do not approach, as both are considered to be very dangerous.'"

At a news conference Sunday afternoon, Maj. Michael Cerretto, Troop A Commander of the New York State Police, said a woman came forth with a "credible description" of the suspects on Saturday.

"We will continue to search this area until all leads are exhausted," he said, also encouraging the public to call with any information, but not to approach the suspects if they are sighted.

Cerretto said authorities were offering a $50,000 reward for information leading to the arrest of either suspect, $100,000 for both.

According to The Associated Press:

"A door-to-door search involving up to 800 law enforcement officers has been underway since then, concentrated in a several-mile radius of woods and fields around the prison in the Adirondacks."State police moved the search command post from the prison Saturday to nearby Cadyville and focused attention on the other side of the state. They advised the public to report any suspicious activity and asked residents who live in the Friendship area along the New York-Pennsylvania border to be on alert."

The inmates escaped from the Clinton Correctional Facility at Dannemora, N.Y., on June 6, by tunneling out of their cell, cutting through a steel wall, crawling through a steam pipe and emerging from a manhole on the outside.

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