A 6-year-old boy who was found under water after he managed to rescue a young friend from a swimming pool has died, according to authorities.

Donald Houser-Richerme (search) died Monday at Advocate Hope Children's Hospital (search) in Oak Lawn, where he had been in critical condition since June 7. The boy saved 5-year-old Karah Moran from drowning in a half-empty pool at an apartment complex in Chicago Ridge. He was under water anywhere from five to 20 minutes.

The boy's mother, Michelle Cartolano, called Police Chief Tim Baldermann on Monday to tell him her son had died.

"That family has been through an awful lot this past week, and throughout the whole ordeal they've shown a lot of dignity, class and strength," said Baldermann.

According to authorities and family members, Donny and two other children discovered the unlocked swimming pool on Monday, and Karah climbed or fell in.

The pool was empty, but five feet of blackened rain water had accumulated at the deep end, and Donny jumped into the shallow end to try to pull the girl to safety. Both slid into the water; Donny helped the girl reach a ladder, but could not save himself.

Authorities said they would not file charges against the owner of the apartment complex after learning a maintenance man had cut the pool's lock.