A manhunt is underway for a possibly armed suspect after a woman was found dead on a Vermont trail, state police said.

Investigators are asking the public to review home and business surveillance systems to help track the suspect as they investigate the "suspicious death," Vermont State Police said on Friday. The death is being treated as a homicide, Major Daniel Trudeau with the Vermont State Police told reporters on Friday.

The victim was found Thursday afternoon on a rail trail in Castleton, police said. Officers responded to a report of a deceased woman around 4:30 p.m. ET.

A witness reported hearing gunshots and seeing a possible suspect headed northbound on the rail trail in the direction of Vermont State University's Castleton campus, police said.

There were no witnesses to the crime itself, Trudeau said.

Residents were urged by police to "remain vigilant" amid the search for the suspect.

"The suspect is in all likelihood armed and dangerous, so should be treated as such," Trudeau said.

State police are asking the public and businesses in the Castleton area to review their surveillance systems for the suspect, from early afternoon into the evening hours on Thursday.

"We have no idea where this gentleman suspect took off," Trudeau said.

Police do not have a suspect identified at this time, he said.

"We're relying on the public to really help us here," Trudeau said. "We really need a good first clue."

The cause and manner of death of the woman will be determined by the Chief Medical Examiner’s Office in Burlington. She has not been publicly identified, though Trudeau said she was not a Vermont State student.

The Vermont State University's Castleton campus is closed Friday and a shelter-in-place order is in effect for those on campus due to the ongoing investigation, the university said.

The suspect is described by police as being a white man, approximately 5'10" with short dark-colored hair. He was last seen wearing a dark-colored T-shirt and carrying a black backpack, police said.

Anyone with information is asked to contact the Vermont State Police at 802-773-9101.