Over the weekend, a man climbed into the bear enclosure at the San Francisco Zoo. Authorities still aren't sure why Kenneth Herron, 21, who is described as a "transient," made his way into the grizzly bear grotto late Sunday afternoon. It seems Herron managed to scale a wall, get himself into the enclosure, and crouch behind some bushes once inside.

San Francisco fire Lt. Mindy Talmadge tells CBS 5/AP, "One bear started to go after him full-stride. He just sat there ... did get close enough to sniff him and put his paw on him."

After staffers arrived on the scene and fired two warning shots in the air, they "secured the bears inside their dens without incident."

Herron, who was rescued without injury, "was not cooperative and also unresponsive." He was also described as "stoic, almost zombie-like." He is currently sitting in a San Francisco jail this morning.

Watch video of the incident after the jump.