A 27-year-old spectator was stabbed several times during the second half of D.C. United's 3-2 shootout victory over the Tampa Bay Mutiny yesterday at RFK Stadium.

Sergio Santino, a resident of the District, was taken by ambulance to D.C. General Hospital and underwent surgery late yesterday afternoon for abdominal wounds, according to D.C. General spokesman Leo Alexander. Santino was in stable condition last night.

No arrests were made, and police said they did not have suspects last night. The knife was not recovered. Lt. L. Gilmore said police had little information from witnesses on a possible motive for the stabbing. "They were not forthcoming with any information," she said.

The victim was stabbed around 3:45 p.m., Gilmore said. No one else was injured.

Neville Waters, marketing director of the D.C. Sports Commission, which operates RFK Stadium, said commission officials would not comment. Waters said the officials plan to use videotapes from D.C. police surveillance cameras scanning the crowd to learn the sequence of events.

"We want to review the videotapes and see the police reports to try to determine exactly what happened," Waters said.

Stadium officials had braced for the possibility of violence yesterday because of the return of former United star Raul Diaz Arce, a native of El Salvador and a crowd favorite who was traded after the 1997 season. In Diaz Arce's first appearance this season at RFK Stadium, in April, a season-high crowd of 35,167 turned unruly. Witnesses reported fights in the stands and parking lots and other rowdy behavior.

In response, stadium officials beefed up security at yesterday's game, with 115 security workers, at least 50 police officers and a full crew of ushers present, a source familiar with stadium operations said. Police patrol cars were a visible presence in parking lots before the game and extra workers were assigned to speed entry into the stadium for fans.

D.C. Mayor Anthony Williams and new Major League Soccer commissioner Don Garber watched the game with United General Manager Kevin Payne from Payne's private box.

Many of the 18,754 in attendance, particularly a large contingent of El Salvadoran fans seated behind the goal at the north end of the stadium, rooted for the Mutiny and Diaz Arce. They also repeatedly booed United stars Marco Etcheverry and Jaime Moreno, who are Bolivian. When Etcheverry failed to convert his turn during the shootout, which took place at the southwest-end goal, a plastic cup and plastic water bottle were thrown from the stands in Etcheverry's direction.

It was in Section 214, in the corner adjacent to the large Salvadoran contingent, where the injured man was sitting, according to one source. The source said the injured man was involved in an altercation that was broken up by security workers, who then ejected several fans from the seating area, including the stabbing victim. Upon reaching the concourse, according to the source, one of the security workers noticed the victim was bleeding.

"It's very unfortunate and it is something we would like obviously to never happen," Payne said. "We had plenty of security today and I think they did a good job and the fans did a good job of policing themselves."

Staff writer Steven Goff contributed to this report.