(CNN) -- State and federal authorities are investigating the apparent double homicide of a U.S. Coast Guard member and a civilian shot dead Thursday on an island off Alaska's coast.
It's possible that the shooter, or shooters, remain at large, according to a Coast Guard statement.
"We're treating this as a double homicide," said FBI spokesman Eric Gonzalez. The slayings occurred inside the Coast Guard Communications Station Kodiak.
Coast Guard investigators, island police, state troopers and the FBI are investigating the incident.
"We are deeply saddened that we lost two shipmates," Capt. Jesse Moore said in a news release Thursday. "This is a rare occurrence, and we are going to do everything possible to ensure we find out exactly what happened."
The victims were identified Friday as Petty Officer 1st Class James Hopkins, an electronics technician, and Richard Belisle, a civilian, who was a retired Coast Guard chief petty officer.
"As an organization with roots in saving lives and a focus on protecting people, this tragic event has shocked us all," Rear Adm. Thomas Ostebo said. "My thoughts and prayers are with the victims' families, their loved ones and the entire Kodiak community."
Their base is on what the city of Kodiak's website calls the second-largest island in the United States, situated in the Gulf of Alaska about 250 miles southwest of Anchorage. The borough of Kodiak Island has a population of about 13,600, according to the U.S. Census Bureau.
The Coast Guard facility normally houses about 60 people.
"It's definitely the topic of conversation right now," said Cheryl Montgomery, a manager at Henry's Great Alaskan Restaurant. "The townspeople are very much on edge here."
Montgomery said that her restaurant remained abuzz Friday with rumors of who may have carried out the shootings, though "nobody knows what's actually going on."
"There's so many weird and bizarre stories running around right now," she said.
City Manager Aimee Kniaziowski said her office has not been instructed to take additional security precautions.
"We're just conducting our business until we're told otherwise," she said.
But the small town is reeling from the loss, she added, calling the killings "devastating."
An elementary school on Coast Guard property went into lockdown mode Thursday morning after school leaders got a call from military police, and students were restricted to their buildings at six other schools.
CNN's Alta Spells contributed to this report.