A woman's complaint that her breast had been squeezed led to the Top One Karaoke firebombing that killed 17 people, a court heard yesterday. The woman inadvertently triggered a battle between Sun Yee On triad members and the bar's bouncers by complaining that she had been groped, an accomplice witness testifying under immunity from prosecution said. '[Accused Tung Shing-fei] said he was singing in the karaoke when [another man] Sheung Tai squeezed the breast of a girl who then summoned the bouncers,' he told the Court of First Instance. Five days later, firebombs were lobbed into Top One's crowded lounge area, choking the rooms with smoke. Also known as 'Ah Fei', Tung, 27, and two other men were yesterday said to have made the deadly bombs out of newspaper, petrol and three beer bottles. The witness, who cannot be identified for his own protection, said he bought the petrol from a Sau Mau Ping petrol station. He then acted as a lookout while three other men made the weapons. 'They filled the bottles with petrol and some waste - newspaper - was taken from the car,' he told the court. 'It was put into the bottle.' He said the bombs were then loaded into Ah Fei's car. Driver Tung, market worker Lee Ka-ho, 22, Cheng Wai-shing, 25, and Lau Ying-tat, 29, both unemployed, have denied murdering the 17 victims. The argument over the squeezed breast broke out on January 20 last year, the court had heard. The bouncers, led by a man claiming Wo Shing Wo triad membership, beat up a group of customers after one said he followed the Sun Yee On. The next day, a group of Sun Yee On 'brothers' were said to have been summoned for a revenge attack, the court had heard. They were instructed to go to the Prat Avenue bar and beat the offending staff members. The attack was called off because of a large number of police patrolling the area. The gang was said to have made a second attempt two days later, but was again put off by police presence. The accused then decided to firebomb the bar, it was alleged. The trial continues before Mr Justice Thomas Gall.