Two suspected triad members active on the fringes of Macau's gaming industry were killed in a nail-bomb attack early yesterday. Four other people were injured in the explosion on Avenida Venceslau de Morais in the densely populated Areia Preta district near the mainland border at about 3.10am. Police sources said the home-made bomb, containing dozens of small nails in a metal box, was targeted at the men it killed - Lai Io-sek, 39, and his bodyguard, Wong Hung-tou, 36. They said it was probably placed in a motorcycle parked on the street and detonated by remote control, killing Wong instantly as he got on to his own motorcycle and fatally wounding Lai in his Honda car. Lai died two hours later in hospital. 'The bomb was meant to kill, no doubt,' said one source. It is understood the dead men were members of the local Soi Fong triad who were leaving a restaurant on their way back to a casino. The blast shattered windows in nearby buildings, waking thousands of people and injuring the three other men and a woman who needed treatment for cuts and bruises. Two motorcycles, a car and a truck were destroyed. A spokesman for the Macau Security Forces said last night that the attack was part of a war between rival gangs on the fringes of Macau's gaming industry. He said the bomb appeared to be the same as a home-made explosive device used in an attack outside a Portuguese restaurant about three weeks ago. No one was injured in that attack. Yesterday's bombing - the worst in recent years - came as a shock as previous bomb attacks were usually small and did not cause fatalities, including one last year when 10 journalists were injured in a twin explosion. Meanwhile, 12 motorcycles and two cars were destroyed in a suspected arson case in Rua Coelho do Amaral near the Chinese Kiang Wu Hospital at about the same time of the bomb attack. A police spokesman said it was not known whether the two cases were related.