A robber let off a firework in front of three customers and five staff in a bank in Tai Po before fleeing empty-handed yesterday. The masked man, wearing a cap and sunglasses, entered the Fortis Bank branch on the first floor of Tai Wo Shopping Mall in Tai Wo Estate and approached the counter at about 2.30pm. Taking a round object about 15cm in diameter from a bag, he threatened a female teller with it and demanded $100,000, a police investigator from the New Territories North regional crime unit said last night. 'Both the robber and teller were apparently panicking at the time. The teller stepped back and the robber then turned and ran off. He lit the object and hurled it to the floor in front of the counter before fleeing out of the bank,' the investigator said. The object - later identified as a firework - exploded, blackening the floor and a wall. The firework contained low-grade explosives and did not cause serious damage. At the time, three customers and five staff were inside the bank. The customers, who were unhurt, left before police arrived. No casualties were reported and the would-be robber escaped empty-handed. Police, including bomb-disposal officers, were sent to the scene after staff pressed an emergency button.