Dr. Donald Liu, a pediatric surgeon at University of Chicago Comer Children's Hospital, dedicated himself to helping children.

On Sunday morning, Liu died while saving two youths struggling in the waters of Lake Michigan off a small beach in Michigan about 90 miles from Chicago, authorities said.

Liu, 50, of Chicago's Hyde Park neighborhood, was on a weekend getaway in Michigan when he noticed two children struggling, University of Chicago Hospitals spokesman John Easton said. "Two kids had been caught in a current, and he went out and saved them both."

Jeffrey Matthews, an oncologist at the U. of C. who was a colleague and friend, said Liu "managed to help them but he got pulled down by the undertow himself. He really died a hero.''

Liu, who recently celebrated his 50th birthday during a surprise celebration, was on vacation with his wife and three young children when he drowned, Matthews said.

Jeff Thornton, a supervisor for the dispatch center for Berrien County (Mich.) Public Safety, said it happened at 9:40 a.m. near Cherry Beach, in Chikaming Township.

Multiple 911 calls were received, and authorities responded to a water rescue, Thornton said. He said the man who died was trying to assist others when it happened.

"It's incredibly sad," Matthews said. "We are so absolutely heartbroken by the loss of our friend and colleague. ... He died saving children, which is what he does every day."

"He was a brilliant, caring, compassionate surgeon and one of the most wonderful people you would ever meet," Matthews said. "He was beloved in the Hyde Park community, and he's just a prince of a man."

Liu worked at Comer Children's Hospital for about a decade, and his colleagues there recently gave him a "distinguished clinician'' award.

"He was a remarkable human being," Matthews said. "He was very passionate about his work.

"What the children needed was always what he talked about. He was a world-class pediatric surgeon who made innovations and advancements in minimally invasive surgery for children and cared for trauma victims."

Liu's death was the first of two apparent drownings in Berrien County, Thornton said. A 41-year-old man from Montgomery, Ill., apparently drowned a few hours later while struggling in the waters.

Tribune reporter Erin Meyer contributed.

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