Authorities continued on Tuesday to search mountainsides for an off-duty Arcadia firefighter, described by colleagues as a well-trained elite athlete, who went missing during a camping trip in Ventura County.
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Searchers in helicopters and on horseback scoured the mountains above Fillmore in search of 36-year-old Mike Herdman.
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"To say it's a needle in a haystack, it's more than that," said Sgt. Eric Buschow of the Ventura County Sheriff's Department. "If he's back there and injured or los or stuck in a spot, we're not going to be able to hear from him."
The seven-year veteran firefighter and paramedic with the Arcadia Fire Department and fellow firefighter Taylor Byars were preparing to set up camp Friday night near a creekbed when Herdman's dog ran away from the camp.
Herdman and Byars went after the dog -- a 50-pound Viszla named Duke -- and became separated, according to department officials who spoke with Byars.
Herdman was barefoot and wearing only shorts and a T-shirt at the time, officials said. Searchers hadn't found the dog. Foul play was not suspected.
"He's in incredible shape," Buschow said. "But even with experience in the back country, if you don't have the right clothing and you don't have the right gear, it can be a tough situation to get out of."
The search was to resume Tuesday morning with mounted patrol officers on about a dozen horses. Crews were "inserted" into the search area by helicopter because walking into the area would require two days, according to the sheriff's department.
Authorities heard about the missing firefighter after Byars hiked for two days out of the deep back country. Searchers found Herdman's backpack and other items at the firefighters' campsite.
"We found his backpack and some footprints and things like that, so they're going to be searching really heavily in that creek bed where he was last seen," said Buschow.
Arcadia Fire Chief Kurt Norwood said Herdman, an elite athlete and family man who planned to be home on Father's Day, was capable of surviving in the wilderness.
"It's tough on the department," Norwood said. "We believe Mike is doing well somewhere and we're waiting for the good news."
A friend told investigators the trip -- the two left Wednesday -- was expected to last four days.
NBC4's Gordon Tokumatsu, Jonathan Lloyd and Toni Guinyard contributed to this report.