THE man said to lead the Sun Yee On triad in Wan Chai and his companion were shot dead in Macau yesterday in an apparent revenge attack connected with their criminal activities in Hong Kong. The murders have sparked fears of all-out gang warfare as rival triad groups battle to fill the power vacuum created in the lucrative nightclub and restaurant district. Andely Chan Yiu-hing, 32, nicknamed the Tiger of Wan Chai, died at the wheel of the van he was about to drive away from the New World Emperor Hotel at 3.10 am. He was hit in the left temple and chest by a spray of bullets fired by three men in motorcycle helmets. Tse Chun-fung, 29, was also hit and died in hospital. Ho Sun-wing, 26, was in critical condition late last night. Chan was a competitor in one of Saturday's Grand Prix car races and Tse and Ho were his mechanics. Two women thought to be accompanying the men were wounded in the shooting. A Hong Kong-based British woman called Gillian Martin, 28, and Nalianee Tokel, 19, from Thailand, were treated for minor leg injuries at the Conde De Sao Januario Hospital but later released. The three men had spent the evening at the bar of the hotel in the outer harbour. Chan reportedly had had a long talk with Hong Kong and Macau merchant and movie producer, Steven Lo Kit-shing. Lo, who sponsored Chan's car in the Tourism Office Cup Race, is the head of the soccer team of Hong Kong's South China Athletic Association and owns the Wing Ko and Regal film companies and automobile businesses. Chan and his companions, also said to be members of the Wan Chai faction of the Sun Yee On, left the hotel at 3.10 am and climbed into their red van. Three men then approached and pumped more than 20 shots into the vehicle from what police believe were either Chinese-made Red or Black Star handguns. Tse was shot in the abdomen and Ho in the chest. Police were on the scene in minutes. Several theories about the killings emerged last night. There was speculation that Chan, who came second in his race, may have been involved in illegal gambling on the races, with some people suggesting more than $1 million was involved. It is said that when Chan was disqualified by scrutineers who found his car had been modified, punters with triad links suffered huge losses. The more likely scenario, however, is that he was killed on the ''neutral ground'' of Macau because of his criminal activities in Hong Kong. Chan was on police bail after being arrested in connection with an extortion attempt on restaurateurs in the Times Square development in Causeway Bay. Tse was wanted by police in connection with the racket and is believed to have entered Macau illegally. Chan was also believed by police to have been responsible for the murder in his hospital bed of film producer Wong Long-wai in May last year. He was arrested in the Kingsway Hotel in Macau for the offence, but later released for lack of evidence. Chan's name was also associated with the singer Anita Mui. In May last year, she was slapped in the face by Wong after refusing to sing during a celebration in a karaoke bar. A few days later, Wong was chopped while leaving a Chiu Chow-style restaurant in Wan Chai. Chan was charged with the assault and was due to appear in court next year. Wong went to the Baptist Hospital for treatment, where a gunman shot him early in the morning of May 7. He died four days later. Although police never charged anyone with the killing, they said they believed Chan was responsible. Wong came to fame for producing the highly-successful Cantonese film, Legend of Chiu Chow Brothers which told the story of the 1960s drug lords, the Ma brothers, who fled to Taiwan. Chan was also arrested but not charged with an attack on the actress Ng Shuet-man this summer after she reportedly refused to do a nude scene in a film. Macau and Hong Kong police immediately linked the shooting with Chan's triad activities, particularly in the film world. Many movie people were in Macau over the weekend for a race sponsored by actor Jackie Chan yesterday. The star said he knew nothing about the shooting and Anita Mui, who was also in Macau, refused to comment. Macau Judiciary Police Sub-Director Albano Cabral said four or five Hong Kong residents were helping with inquiries and Interpol and the Hong Kong police had been asked to help. Wan Chai Assistant District Commander Jimmy Leung Hung-wai, who led the team of policemen who arrested Chan and 17 others earlier this month over the alleged Times Square extortion racket, said he felt sure the killings were connected with the men's criminal activities in Hong Kong - in particular, Wong's murder. ''His activities must have been upsetting a lot of people but as to which incident prompted this, I am not sure. Chan was involved in so much recently. ''My suspicion is that it was connected with the murder of Wong. The triads believe in an eye for an eye. A rival group may have come after him over that. ''This solves a problem for us,'' he said. Asked whether a member of the Sun Yee On could have been behind the killing, Mr Leung said: ''It's very rare for the Sun Yee On to kill their own. If they do, it is normally punishment for disloyalty to their leader.'' Mr Leung said that Wan Chai police would be happy to assist Macau police in their inquiries and would be prepared to offer them background information on the triads if asked. He also warned of a possible outbreak of gangland violence in Wan Chai caused by Chan's death. ''Wan Chai police are very alert to the possibility that rival triad groups may try to take over Sun Yee On activities as a result of these killings. ''We will be keeping an eye on them. We are aware there may be increased tension.'' The Sun Yee On was the most powerful triad group in Wan Chai. Its rivals are the 14K and the Wo Hop To. Ironically, Chief Inspector David Lorimer of Wan Chai police, who also played an important part in the arrest of Chan, was in Macau over the weekend acting as a marshal for the Grand Prix.