Firefighters are responding to a rattlesnake bite call on Iron Mountain Trail.
An adult man called for help saying he's about one hour up the trail and needs rescue.
The trailhead is at the intersection of State Route 67 and Poway Road.
An hour after the call, Poway firefighters said they have been unable to locate any hiker who called 911.
The search was called off later in the morning. Two helicopters, two engines, and an ambulance were called out, and firefighters hiked to the top of the mountain looking for the man.
Authorities tried calling his cell phone back, but it went straight to voicemail.
They believe he either went to a hospital on his own or the call was a hoax.
In any case, firefighters warn hikers to be on the look out for rattlesnakes on local trails, and to always carry a cell phone. If possible, hike in pairs, they say.
"Here in the City of Poway, in the last three days, we've received ten calls for service for rattlesnake removal," said Mark Sanchez, Poway Director of Safety Services. "The heat is bringing them out. And they enjoy the shade."