Police tightened security Sunday and resumed investigating the fatal stabbing of the father of a former Olympian, an attack that stunned the athletic community and embarrassed Chinese authorities determined to hold the most successful Summer Games ever. Todd and Barbara Bachman of Lakeville, Minneapolis – parents of 2004 volleyball Olympian Elisabeth “Wiz” Bachman and in-laws of US men's volleyball coach Hugh McCutcheon – were attacked by a Chinese man while visiting the 13th-century Drum Tower on Saturday. The assault came only hours after the spectacular opening ceremony for the games. The US Olympic Committee confirmed Bachman died from knife wounds and that Barbara Bachman suffered life-threatening injuries. She and their Chinese tour guide, who was also injured in the attack, were being treated in a Beijing hospital. The committee said Sunday that Mrs. Bachman suffered multiple lacerations and stab wounds. She underwent eight hours of surgery and was in critical but stable condition. The statement said family members were at the hospital and that McCutcheon would “not be on the bench today” for the US men's volleyball team's opening game against Venezuela. Rob Browning, team leader of the men's volleyball team, said the team was united in supporting the Bachmans. “We are absolutely devastated by what has occurred, for their loss and for everything they are going through,” Browning said. “We are a family, and we'll get through this together as a family.” US President George W. Bush, in the Chinese capital to attend some Olympic events and meet with Chinese leaders, thanked the communist regime Sunday for its handling of the attack. “Your government has been very attentive, very sympathetic, and I appreciate that a lot,” Bush told Chinese President Hu Jintao before they met for private talks at the presidential compound. Hu said his government took the incident “very seriously” and pledged to keep Washington apprised of the investigation. Elisabeth Bachman was with her parents at the time of the attack, but uninjured. Her father was chief executive officer for Bachman's, Inc., a home-and-garden center based in Minneapolis. Shortly after the attack, the assailant, Tang Yongming, 47, leapt to his death from a 130-foot high balcony on the Drum Tower, just five miles from the main Olympics site, the official Xinhua News Agency reported. Dale Bachman, Todd's second cousin, told a news conference in Minneapolis that the next 24 hours would be critical for Mrs. Bachman. He said two of Todd and Barbara Bachman's other adult daughters were flying to China to be with their mother and Elisabeth. He said Todd Bachman was walking a few steps behind his wife and daughter at a Beijing tourist site when he was attacked by a knife-wielding stranger. Barbara Bachman heard the commotion and turned to help her husband. “That's when she was attacked,” Dale Bachman said. “To me, that was a strong indication of her love. She is a fabulous person.” The midday attack sent shock waves through the games precinct after the Olympics' spectacular opening ceremony had set an ebullient tone. US Olympic officials met with the women's beach volleyball players and warned them about going out, reminding them that if they must, they should avoid advertising themselves as Americans.