MINNEAPOLIS - An early morning adventure took a dicey turn for a man in the warehouse district of Minneapolis Tuesday, forcing the fire department into rescue mode.

Police say the man and a friend, both in their 20s, climbed down into the tunnels belowthe Pillsbury "A" Mill on Main Street and 3rd Avenue Southeast around 3 a.m. to explore. That's whenone of the men suffered what authorities are calling "muscle fatigue," leaving him unable to climb out.

His friend then left the man behind to call 911 and wait for authorities. First responders went in through the elevator to access the tunnel and brought the man back out around 5:30 a.m. He was able to walk to the ambulance under his own power, and was taken to Hennepin County Medical Center to get checked out.

Rescuers say the tunnel was about 3 feet wide and had cold sitting water in it.

Both men could be cited for trespassing.