More than 1,000 law enforcement officers are on a manhunt for David Sweat, the remaining escapee of an upstate prison three weeks ago.

Sweat's accomplice, Richard Matt, was shot and killed by Border Patrol agents Friday when he refused to raise his hands and drop a shotgun, officials say.

Police have formed a perimeter in the woods outside of Malone, New York, which is about 40 miles away from the Clinton Correctional Facility, where Matt and Sweat had been serving sentences for murder.

Police are patrolling the area guns in hand. Other officers are manning security checkpoints on the roads, stopping drivers and searching cars.

Police say the heavy presence is necessary with an escaped killer on the run. Area residents say they're growing weary of the unease.

"It's been awful," one resident said. "I can't sleep, and then darkness hits. I'm wondering where they are, what they are doing and how they got out."

Police say they believe Sweat's resolve may be wearing down in the woods with little food and water. He's also lacking the support of his accomplice.

Police say a 911 caller reported hearing gun shots Friday. When law enforcement agents arrived at the scene, they say they found evidence that Matt was nearby and were able to track him down.

"As we did the ground search, we heard coughs," says Joseph D'Amico, the New York State Police superintendent. "Teams met up with Matt in the woods; challenged him. He was shot dead by Border Patrol. We recovered a shotgun from Matt's body at the location."

Police say they have no reason to believe Sweat was not nearby.