Talladega County Sheriff Jimmy Kilgore said Wednesday that other law enforcement agencies have joined the search for 28-year-old Nicholas Bower of Villa Rica, Ga.
Bower came to the NASCAR race at Talladega with his girlfriend, but has not been seen since, The Daily Home newspaper reported.
"I'm asking everyone to check all your tents, vehicles, RVs, everything. Then double check," said his girlfriend Jennifer Boesch.
She said she awoke around 12:30 a.m. Sunday, and Bower was gone. Boesch said he had "never done anything remotely like this."
There's been no indication of foul play, but authorities say they don't know what happened.
"We are using all the resources available to us," Kilgore said. "And we have called in other agencies."
"We're still pursuing all avenues, and if anyone knows anything, please come forward," the sheriff said. "I'm sorry there's not much more detail I can give, but I do want to thank everyone that supported the search."
Information from: The Daily Home - Talladega, http://www.dailyhome.com
Copyright 2013 The Associated Press.