NORRIDGEWOCK, Maine -- A gunman in Maine killed a sheriff's deputy, stole his cruiser and robbed a convenience store early Wednesday, triggering an intensive manhunt in a heavily wooded rural town, officials said.

Somerset County Cpl. Eugene Cole was killed around 1:45 a.m. on U.S. Route 2 in Norridgewock, about 60 miles west of Bangor, state police said. His cruiser was driven to a Cumberland Farms store, which was robbed.

A manhunt is underway for John Williams who is accused of killing Cpl. Cole of the Somerset County Sheriff's Department in Maine. He is considered armed and dangerous. He's approx. 5'6', and 120 lbs. Anyone with information about his whereabouts is asked to call 207-624-7076. pic.twitter.com/Q9vJlGqAIY — FBI Boston (@FBIBoston) April 25, 2018

Aircraft and armored vehicles were seen around Norridgewock, and schools were locked down as federal, state and local law enforcement officials searched for 29-year-old John Williams, of Madison, Maine, who remained on the loose after abandoning the stolen cruiser, state police said.

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"Many times we're able to say that there is not an ongoing threat, but that's not the case today," said State Police Lt. Col. John Cote. "There certainly is an ongoing public threat. He's considered armed and dangerous."

Several Somerset County officers arrived on scene within 10 minutes after the robbery, and the cruiser was found abandoned shortly after 5 a.m. in another part of the town. It wasn't known if the man was driving another vehicle.

Police said Williams is 5-foot-6, 120 pounds with blue eyes and brown hair in a ponytail.

NEW: ME State Police release updated photos of suspect John Williams, also captured walking into gas station after he allegedly killed cop pic.twitter.com/kMgXVZ4NQe — Marissa Bodnar (@MarissaWGME) April 25, 2018

Maine records didn't indicate a lengthy criminal record. But Williams had been arrested last month in Haverill, Massachusetts, for carrying a firearm without a license and possession of a large-capacity firearm, officials said. He was due to return to court Wednesday in Massachusetts.

Residents of the town of about 3,500 people were urged to be vigilant. There are heavy woods in the area.

"We're a little on edge. It's unnerving knowing there's a guy running around out there," said Tasha Raymond, who was home with her two children.

Cole's death is believed to be the first killing of a law enforcement officer in Maine in nearly 30 years. The last time an officer was killed in the line of duty was in 1989, according to the Maine Department of Public Safety.

Gov. Paul LePage expressed his "deepest condolences" to Cole's family in a tweet. "If you live in Somerset County and the surrounding area, please cooperate with law enforcement and stay safe," the Republican governor said.

Cole has a son who also is a Somerset County deputy. Sheriff Dale Lancaster called Cole, a 13-year veteran of the department, an "outstanding employee, one of the finest deputies."

Anyone who sees Williams is urged not to approach him, but to call 911. Anyone with information about his whereabouts is asked to call 207-624-7076.