SAN JOSE, Calif. (KGO) -- A southern California businessman has made a $5 million donation to the San Jose flood relief fund.Billionaire Philanthropist Kieu Hoang flew the check to San Jose on Wednesday.San Jose city officials were stunned by the huge contribution that will help put a dent in the $73 million in estimated damage from the Coyote Creek floods last month.Apparently, Mr. Hoang and Mayor Sam Liccardo talked on the phone this week about the big job ahead to bring the city back to normal after the floods"I asked him approximately how much it would cost, he told me about $5 million. At first, I told him I have $2 million," said Hoang.The money was not a stretch for Hoang, who at the age of 73 is committed to curing cancer and housing the homeless.In 1973, Hoang immigrated from Vietnam and eventually started a biotech company.His donation now brings the flood relief fund from $1 million to $6 million."Today, he is helping enormously to heal San Jose and we are so incredibly grateful for his philanthropy here today," said Mayor Liccardo.Mr. Hoange took a short walk around the Rocksprings neighborhood Wednesday. Many of the residents are immigrants from Vietnam, just like him.The Mayor outlined for him, how the money would be used. "Housing, trying to clean up the water. Right now everyone is in a rush to move in," said Hoang.Hoang says he plans to hold the mayor accountable for making sure the money goes directly to flood victims.