Hong Kong's security chief warned that laws on the possession and use of firearms and ammunition may need to be tightened after police found an arms cache in a Sham Shui Po flat. More than 100 real and imitation firearms, tear gas grenades, a mortar, mortar shells and thousands of rounds of ammunition - some which could pierce a bulletproof vest - were uncovered after police were called to the flat of a 63-year-old retired Correctional Services officer on Friday night. The ex-prison guard, who is a gun collector, accidentally shot himself while cleaning a rifle. He is in a serious condition in Princess Margaret Hospital. He was arrested last night. A 59-year-old woman was also arrested for possession of arms and ammunition without a licence. She was released on police bail to report back later this month. Police said the man had a licence to own up to 10 firearms, and the discovery of the huge weapons haul worried secretary for security Ambrose Lee Siu-kwong. 'I think many people are concerned about the case,' he said. 'In Hong Kong, it is a serious offence to store and use guns illegally,' he said. Asked if the present laws were sufficient to deter such crimes, Lee said authorities would consider whether existing regulations needed strengthening. 'We should remember it is not only about how strict the laws are, it is also about if people abide by them.' Police took away more than 20 boxes of guns and ammunition and were last night examining them. Officers believe about 20 of them are genuine and the rest replicas. Sham Shui Po Assistance District Commander Lau Tat-keung expressed concern over the high-velocity bullets found. 'It's quite scary. Some of these weapons are not allowed to be possessed by people even if they have the permission to store and use guns. It will take at least a day for us to do the calculation. Our initial estimation is that there are over 1,000 or even close to 3,000 bullets,' he said.