A Pennsylvania prison fugitive has armed himself with a stolen rifle, police warn, as the manhunt for the murderer stretches into its 13th day.
A police spokesman told a news conference Danelo Cavalcante may be "desperate enough to use that weapon".
Officials say the resident gun owner fired a pistol at him as Cavalcante fled. But he is believed to have escaped the shoot out unscathed.
Residents have been urged to secure their property and vehicles.
More than 500 officers are poring over a roughly 10 sq mile (26 sq km) perimeter in South Coventry Township, north-west of Philadelphia.
Cavalcante, a Brazilian national, was sentenced to life in prison last month for killing his ex-girlfriend.
But just a week after his sentence, the 34-year-old fled Chester County Prison on 31 August by "crab walking" between two walls, scaling a fence and crossing razor wire.
Over the weekend, authorities said he had shaved his beard, stolen a local dairy farm's van and visited the homes of two former work associates.
In spite of multiple sightings, Cavalcante continues to evade arrest.
On Monday night, a female motorist in South Coventry Township told police she may have spotted him crouching by the tree line along a road.
Officers who fanned into the area overnight found footprints that led to the recovery of the convict's prison shoes, as well as a green sweatshirt and white T-shirt he had apparently taken off.
A local resident also reported that his work boots had been stolen from the porch of his residence.
Police said Cavalcante had entered the open garage of another residence and fled with a .22 calibre rifle, equipped with a scope and a torch, as the homeowner fired several shots from a pistol at him.
"We've always considered him to be a risk," Pennsylvania State Police Lieutenant Colonel George Bivens told a news conference on Tuesday. "We now have confirmation he has a firearm."
Lt Bivens said there was no evidence to suggest Cavalcante had been injured by the homeowner's gunfire.
He added: "He has killed two people before. I'd suspect he's desperate enough to use that weapon."
A local farmer told CNN he had heard "about seven low calibre shots in quick succession", which he said was out of the ordinary so late at night.
Tactical search teams from at least six entities, including the FBI and US Border Patrol, as well as canine teams, mounted patrols and helicopters, are fanning through the area in pursuit.
But the area is heavily wooded, on hilly terrain, and comprises creeks and other obstacles that could complicate the search.
"Just because we find a footprint doesn't mean we know which way he went," Mr Bivens told reporters. "We don't have the luxury of charging up the nearest trail and hoping that's the way he went."
Roads in South Coventry Township, as well as the local Owen J Roberts School District near the search area, have been closed.
On Tuesday afternoon, Pennsylvania Governor Josh Shapiro expressed confidence that the fugitive would soon be apprehended, calling on him to surrender.
"This is a moment you have to realise that the gig is almost up," he said.
The governor added there would be questions that county officials "are going to have to answer" once the manhunt ends.
A reward for information on Cavalcante's whereabouts has increased from $20,000 to $25,000.
He was convicted earlier this year of killing Deborah Brandao, stabbing her 38 times in front of her two young children in April 2021.
Brandao's family is under 24-hour police protection. Her sister, Sarah Brandao, told CNN she had not slept for days since his escape.
She said Cavalcante and her sister met when they were neighbours in Chester County, but he became jealous and angry.
He is also wanted in his home country in connection with a 2017 murder in the central Brazilian state of Tocantins.
Details of his case, shared by TV Globo, allege he was involved in fights as a teenager and murdered a young friend over an unpaid debt.
After shooting his friend and checking that he was dead, he took the victim's mobile phone, the outlet reported.
Cavalcante's prison break and his fortnight on the run have generated headlines back in Brazil.
Additional reporting by Mariana Sanches, BBC Brasil