Norman Johnston, who escaped from a Pennsylvania prison earlier in the week, is considered "armed and extremely dangerous," state police Lt. David M. Presto said.
Authorities said it was likely that he has left the Nottingham area in a silver Buick that was stolen Friday night.
Local residents described a cautious and curious mood.
"Some people are locking their door," resident Jim Murray said as he stopped outside a convenience store. "There's a lot of curiosity because this is a town that doesn't get a lot of attention."
Johnston, 48, was spotted talking on a pay phone Friday night but escaped into the 600-acre Nottingham County Park after a scuffle with one of the rangers, said state police Capt. Henry Oleyniczak.
Johnston was convicted in 1980 of killing four teen-agers to cover up a multimillion-dollar burglary ring he ran with his two brothers. The film At Close Range, starring Sean Penn, was based on the case.
He escaped Monday from a prison where he was serving a life sentence. Police said he opened the window in his cell, sneaked across a grassy yard and wriggled through a fence at the maximum-security complex.