The search for two missing firefighters — one from Fairfax County, Virginia — in the Atlantic Ocean off Florida is in its fifth day, and the U.S. Coast Guard said it was “optimistic, but guardedly so” about the efforts to find them.

Justin Walker, a master technician for Fairfax County Fire and Rescue, was last seen Friday heading out on a fishing trip with his friend Brian McCluney, a Jacksonville, Florida, firefighter. They left Friday morning from Port Canaveral on McCluney’s 24-foot center console boat. The Coast Guard was called late Friday night when they didn’t return.

“We’re continuing to search, and we’re searching heavily,” said Capt. Mark Vlaun, of the Coast Guard’s Jacksonville Sector, at a news conference Tuesday.

He said the search area covered 50,000 square miles, and that searchers were focusing on the area about 50 miles east of St. Augustine, around where a tackle bag was found that McCluney’s family confirmed was his.

“That’s a large data point” that, combined with computer modeling and re-creation of tidal drift, allows the search to focus on the area between St. Augustine, Florida, and Savannah, Georgia, rather than farther north, Vlaun said.

They know when the two left and they know the timing of a cellphone ping off Cape Canaveral at a well-known fishing area, he added.

Searchers are scouring the one photo they have of the boat, identifying what the two left with on Friday. “We haven’t had any conversations with anybody who saw them that day.”

Vlaun said that for the Coast Guard and other searchers, the search is “absolutely, 100% a rescue operation.” That said, each day, they look at what they found the day before and decide whether to continue.

“What will we find today? What will tomorrow look like?”

‘We remain optimistic’

Fairfax County Fire and Rescue said in a statement Monday afternoon that the department is in contact with Walker’s family and Jacksonville Fire and Rescue.

“We remain optimistic that they will be found,” the department said. “We are working closely with authorities in Florida to provide assistance and coordinate any resource needs. Please keep these firefighters, their families and friends in your thoughts and prayers.”

Fairfax County Professional Firefighters & Paramedics President Ron Kuley said that his organization is cautiously optimistic. “It gets a little emotional thinking about this. It’s a very difficult situation, but we’re hoping for a positive outcome,” he said.

Kuley thanked all the people who are searching for the men, saying they have been doing an “extraordinary” job.

“Our brothers out there are alive and they’re going to be found,” Kuley said. “We just need a lot of positive energy and prayers.”

WTOP’s Nick Iannelli, Teta Alim and Abigail Constantino contributed to this report.