Six-year-old Donnie Hauser-Richerme knew he couldn't swim, but he also knew the little girl in the murky, debris-filled swimming pool (search) was in trouble.

Donnie jumped in and helped save 5-year-old Karah Moran's life before becoming stuck in five feet of blackened rain water and muck at the bottom of the deep end.

Paramedics (search) eventually rescued him, but he was in critical condition and on life support (search) Thursday.

Karah called Donnie "my hero."

"I can't say enough about this little guy," said Chicago Ridge Police Chief Tim Baldermann. "It's amazing that this little kid, old enough to understand it's a dangerous situation, was so brave. Without thinking about himself he instinctively jumped in to help his friend."

The rescue happened Monday as Karah, Donnie, and his 4-year-old brother explored the apartment complex where their families live. Karah, who was visiting her grandmother at the complex, knew the location of an empty swimming pool on the grounds.

"She wanted to show the pool," said Karah's aunt, Bernadette Choate. "She didn't expect the gate to be unlocked."

A maintenance worker had been sent out to the pool that day to do some work, Baldermann said. Faced with a locked gate and no key, the worker cut the lock to get in. He wrapped a chain around the gate and left, but the children were able to remove the chain and get inside.

Karah either climbed or fell into the pool's shallow end, where there wasn't any water. But the bottom was slick with dead leaves and algae, causing her to slide down into the muck-covered deep end.

Donnie jumped into the shallow end and reached toward his friend to try to pull her to safety. But Karah weighs about 10 pounds more than Donnie, and between the weight and the slick surface, the boy slipped and both ended up in the water.

Karah's mother, Melany Moran, said her daughter told her that as the two were struggling in the water, Donnie helped her reach the ladder.

As somebody called 911, adults hurried to the pool area, but the water was so filthy, so filled with debris, that they couldn't see Donnie. Another maintenance man, Andre Mitchell, said he poked the water with a long aluminum pole used to clean pools but turned up nothing.

By the time the paramedics found Donnie, he had been under water anywhere from five to 20 minutes, Baldermann said.

He said prosecutors decided not to file charges against the owner of the complex after learning the maintenance man had cut the lock.

Melany Moran said she is worried about her daughter and plans on getting her into counseling "when this all dies down."

"Last night she had a nightmare," she said. "She was screaming, 'Help me, help me."