An off-duty sergeant fired three shots as a gunman took aim at him and another man tried to attack him with a knife in a remote car park in Tai Po early yesterday. Lam Kin-keung, 54, who is due to retire soon, missed his two targets and twisted his ankle while running for cover. Last night police were still hunting the two attackers, who are thought to be in their 30s. A police officer involved in the investigation said the station sergeant probably disturbed the two men as they tried to steal a truck or take valuables from vehicles in the car park near the village of Sheung Wun Yiu. A villager said her nephew's crane truck was stolen from the car park recently and she suspected the two men were the culprits. 'They probably came back to steal,' she said. She hoped the police would step up patrols in the area. The incident happened at about 2am when the officer drove back home and parked his car in the open car park near Cheung Uk Tei off Tat Wan Road. He had finished his shift at 7pm and visited a friend on Sunday night before going home. In the car park, he saw a man acting suspiciously near a goods vehicle and went to investigate. He pulled his gun when the man drew a knife from a plastic bag. He declared himself as a policeman and shouted at the man to stop, according to Tai Po acting Superintendent Simon Leung Wai-bun. 'As the man tried to attack him with a knife, the officer issued a warning. The man ignored the warning and tried to attack him. The station sergeant fired a shot,' he said. 'After the shooting, the man did not stop and tried to attack again. The officer fired another shot.' Police said they were at a distance of three metres. At the same time, another man shouted loudly on the other side of the officer. The sergeant turned and spotted the man about 10 metres away, hiding behind a truck. 'He found this man carrying what appeared to be a handgun and taking aim at him,' Mr Leung said. 'Our colleague stepped back and took cover at the back of a car. As he found the gunman still taking aim at him, he fired the third shot.' As no blood was found at the scene, he believed the three shots missed. The officer dialled 999 after the attackers fled on foot. He was treated at Alice Ho Miu Ling Nethersole Hospital. At about 3am, more than 60 police officers armed with shotguns mounted a search. A tracker dog was also used. Another 40 officers in camouflage searched a nearby hill at about 8am, but no one was arrested. At the scene, police found two fruit knives, a screwdriver, a cap and a pair of gloves near the plastic bag, which also contained a linen bag and a metal rod. A police investigator said the sergeant was justified in opening fire as the two men had tried to attack him. Police appealed for witnesses to call 3661 3545 or 3661 3600. It was the second time in five months that a police officer has opened fire. In March, a Nepali man was shot in the head by a constable in Ho Man Tin after the man attacked him with a chair. Sergeant Lam, who has been in the force for about 33 years, is attached to the Hong Kong Island crime unit. He was recently awarded the Hong Kong Police Medal for Meritorious Service. An elderly villager said she had lived in Sheung Wun Yiu for more than 30 years and it had always been peaceful. But a grocer said villagers now seldom left their doors open.