Throughout Monday and into Tuesday morning, doctors, nurses and medical technicians at Comer Children's Hospital worked to keep Jonylah alive, Dr. Slidell said.

Around the time of the shooting, Jonylah's mother, Judy Young, said she was finishing up her shift at a nearby McDonald's.

She said a manager, alerted to the tragedy by Young's relative, called her into his office to break the news.

She was escorted by police to the hospital, where she said she camped out in the waiting room for hours, praying for the survival of her daughter, nicknamed "Smooch."

But doctors eventually told her that the prognosis didn't look good.

The doctors "did everything they could," Young said. "I told them, 'I don't want my baby to suffer.'"

At 6 a.m. Tuesday, Jonylah was pronounced dead.

Young said she vividly remembered the September day her daughter was born.

"I was barely in labor," said Young, calling Jonylah a "happy baby."

Tribune photographer Nancy Stone and reporters Hal Dardick, Liam Ford and Jason Meisner contributed.