COOKE CITY, Mont. -- Ronald Singer was deep asleep at a Montana campground when he lurched awake to something gnawing on his leg.

"The tent flies 2 to 3 feet. This thing's on my leg. It was terrifying," the 21-year-old Alamosa man told TheDenverChannel.com Thursday. "I was sound asleep. I had no idea what it was."

The ex-high school wrestler just started raining blows on the growling grizzly bear in the dark.

"It was basically instinct. I just started punching it," he said. "I have no idea where I hit it. I didn't really aim. I just threw punches and wherever it landed, it landed."

His girlfriend, Maria Fleming, screamed and the bear disappeared in the darkness through a hole in the tent.

Singer was relatively lucky.

The rampaging mama grizzly killed a Michigan man and left a Canadian woman with crushed bones and severe lacerations in her arms and deep bite wounds in her leg during the 2 a.m. Wednesday attack, which occurred at Soda Butte Campground near Yellowstone National Park.

Singer escaped with deep bite wounds in his calf and a dent in his shinbone where the bear chomped him. He was treated at a Cody, Wyo., hospital and released.

Just hours after the mauling, he was cracking jokes about the ordeal.

"Damn bears, I am not a free meal!!!" Singer, a 21-year-old engineering student at University of Colorado Denver, declared on his Facebook page.

A day after the attack, Singer was back on vacation, checking out Old Faithful and planning on some fishing.

But with his tent shredded, he, his girlfriend and her father and sister were sleeping in a motel.

"I'm probably not going to go tent camping in bear country. Other than that, I'll still go camping," he said.

Singer agrees he came out of the bear battle with a life-long story to tell.

And "pretty gnarly scars to show, too," he said.

Montana Fish and Wildlife agents have trapped a mother bear and three cubs in that area. The wildlife agents will use DNA to make sure they have the right bears.