Cops hunting for two escaped murderers were zeroing in early Thursday on a 3-mile area not far from where the dangerous duo broke out to freedom six days ago.
Police pursuing a lead shut down a state road near the Clinton Correctional Facility, though there was still no sign of Richard Matt or David Sweat as dawn broke in Dannemora, New York. Officials said that the stretch of Route 374 would likely remain closed through Thursday morning.
Officers focused on that area after a police dog picked up the scent of one or both of the escapees late Wednesday, a senior source familiar with the investigation told NBC News.
Matt and Sweat were reported missing early Saturday morning — but authorities conceded they could have escaped hours before anyone noticed they were gone.
New York State Police Superintendent Joseph D'Amico conceded Wednesday that he had "no information on where they are or what they're doing, to be honest," despite the hundreds of tips that have poured in.
The nearly 500 law-enforcement offices involved in the manhunt were doubling down on searches near the prison where Matt and Sweat carried out their "Shawshank Redemption"-style escape, armed with assault rifles and sniffer dogs as they retraced grid searches for the fugitives.
Corrections officers armed with shotguns kept their hands on their triggers while manning a roadblock early Thursday around three miles from the manhole cover where Matt and Sweat broke through to freedom.
Nearby checkpoints along the perimeter of the search area were staffed by a minimum of three state troopers, who examined each approaching car.
NBC station WPTZ of Plattsburgh reported that residents in the area were being urged to stay in their homes and to turn on their exterior lights.
Meanwhile, authorities in Vermont were on high alert after officials said there was information the fugitives might have headed to the neighboring state.
"We have information that suggests they thought New York was going to be hot. Vermont would be cooler, in terms of law enforcement," Vermont Gov. Peter Shumlin said on Wednesday.
Police in Philadelphia questioned a cab driver who believed he might have picked up the two escaped murderers, according to NBC Philadelphia. Police later said the tip was unfounded.
New York Gov. Andrew Cuomo vowed Wednesday: "I am confident we will find them. The only question is when."
Canadian authorities also have expanded their own search, law enforcement sources on both sides of the border told NBC News.
The initial focus for the Canadians was along 100 miles of the border north of the prison, but it has expanded east and west, along Canada's border with New York, Vermont and New Hampshire, the sources said.
