John Williams remained at large Wednesday afternoon, with authorities warning the 29-year-old suspect is likely "armed and extremely risky".
"Many times we're able to say there is not an ongoing threat".
The suspect, John D. Williams, 29, of Madison, is still at large and is armed and considered risky, Lancaster said. The suspect in this crime allegedly shot Somerset County Corporal Eugene Cole at about 1:45 a.m., drove off in his police cruiser, and then robbed a Cumberland Farms convenience store.
State police said that Somerset County Cpl. It wasn't known if the man was driving another vehicle.
NBCBoston reports Williams was arrested in March for several firearms charges and traffic violations in Haverhill, Massachusetts. He is described as about 5 feet 6 inches tall, 120 pounds with brown hair with the sides shaved and a pony tail on top.
Residents of the town of about 3,500 people were urged to be vigilant. "It's unnerving knowing there's a guy running around out there", said Tasha Raymond, who was home with her two children.
The last ME law enforcement officer to die in the line of duty was an Fryeburg officer Nathan M. Desjardins in June 2017, according to BDN archives.
According to information released by the Department of Public Safety, a nationwide alert for Williams has been issued and a manhunt is underway. Cole, a 13-year veteran on the force, reportedly has a son who also serves as a sheriff's deputy.
Gov. Paul LePage expressed his "deepest condolences" to Cole's family in a tweet.
"He was one of the finest deputies that you would want to meet", Fox News quoted Lancaster from a news conference. "If anyone sees Williams they are told not to approach him but call 911".