Last Updated Jun 11, 2015 10:24 AM EDT
DANNEMORA, N.Y. -- Authorities searching for two escaped killers who have been on the loose for the better part of a week converged late Wednesday around a tiny upstate New York town five miles east of the maximum security prison the two broke out of.
CBS News' Don Champion tweeted early Thursday about a roadblock set up near Cadyville, New York.
A helicopter was circling overhead Thursday morning, CBS News correspondent Anna Werner reports from West Plattsburgh, just outside Cadyville. Dense fog, which was lifting as the morning wore on, blanketed the area overnight. Police set up bright flood lights to help with the search. People in the area were reportedly told to remain inside with their doors locked.
The Saranac Central School District will be closed Thursday.
The Plattsburgh Press-Republican reports local residents say evidence of criminals "bedding down" was found in the woods.
Earlier Wednesday, the search was expanded to neighboring Vermont after investigators learned the inmates had talked before last weekend's breakout about heading there.
"We have information that suggests they thought New York was going to be hot. Vermont would be cooler, in terms of law enforcement," said Vermont Gov. Peter Shumlin, at a Wednesday news conference along with New York Gov. Andrew Cuomo.
He and other officials would not say how authorities learned that information.
New York State Police Superintendent Joseph D'Amico said a prison employee -- identified by CBS News as Joyce Mitchell, a training supervisor at the prison tailor shop -- had befriended the killers and "may have had some role in assisting them."
He would not elaborate.
CBS News senior investigative producer Pat Milton reports a law enforcement source confirmed that a female prison employee allegedly was supposed to pick up the two inmates after they escaped, but she didn't show up. The source said she allegedly went to a hospital instead, apparently suffering from a panic attack.
When she got out of the hospital, the source said, she went to authorities and allegedly told them of her involvement in the escape plans.
She allegedly has been providing some good information to authorities. But she allegedly did not know the escapees' entire game plan or what they intended to do if she didn't show up to drive them away.
The source said she is also believed to have allegedly assisted in some way with acquiring the power tools the pair used to escape.
Inmates David Sweat and Richard Matt cut through a steel wall, broke through bricks and crawled through a steam pipe before emerging through a manhole in the street outside the 3,000-inmate Clinton Correctional Facility in Dannemora, in far northern New York, about 20 miles from the Canadian border.
The breakout was discovered early Saturday, meaning the inmates may have had a head start of several hours, Cuomo said.
Unions representing guards and civilian staff members at the prison said many have been questioned by investigators but no one has been suspended, disciplined or charged.
Authorities have fielded hundreds of tips since the breakout from the prison, which is about 20 miles from the Canadian border.
In Philadelphia, a cab driver said he picked up two men matching the descriptions of the missing inmates around 4:15 a.m. Thursday and dropped them off at the city's Amtrak station, but the police commissioner said he had no reason to think the inmates were in the city.
Vermont authorities were patrolling Lake Champlain and areas alongside it, Shumlin said. Cuomo urged the people of Vermont to be on the alert and report anything suspicious, warning: "Trust me, these men are nothing to be trifled with."
As part of the search, state troopers and correction officers in helmets and body armor retraced their steps around the prison, checking garage doors, sheds, windows and other structures for signs of a break-in or other clues.
More than 450 federal and state law enforcement officers were taking part in the search, including customs agents, federal marshals and park rangers.
New York State Police closed a road east of Dannemora late Wednesday to investigate a lead involving the escapees. The road was expected to remain closed through the morning, state police said in a statement.
The killers' mugshots have been put on more than 50 digital billboards in New York, New Jersey, Massachusetts and Pennsylvania, state police said, and a $100,000 reward has been posted.
Law enforcement officials again asked the public to report anything out of the ordinary.
"We don't want them out searching the woods," Sheriff David Favro said. "But if you're sitting on your porch, get your binoculars out and see if you see something unusual."
In Dannemora, Barbara McCasland said officers asked to search her home but she told them no.
"I'm pretty battened down here," she said. "My windows are locked and everything."
As the manhunt dragged on, she said she was getting worried: "I wasn't in the beginning, but seeing that they've been out there so long, I am a little nervous."
Many in the prison town greeted the return of the searchers with a shrug. Many suspect Sweat and Matt are long gone and they are past any danger.
"I'm not worried about it," Jackie Trombley said.
Referring to the searchers swarming the area, she said: "We've got these guys down the road. They're everywhere, so it really doesn't bother me."