Police cordon off the road near a school where two fully functional home-made bombs are found in Hong Kong, China, Dec. 9, 2019. (Xinhua)

The Hong Kong police said on Monday night that they have successfully defused two home-made remote-controlled bombs inside a school which were fully functional and may cause multiple casualties.

The police received tip-off at around 5:30 p.m. on Monday local time that two suspected bombs were found inside the campus of Wah Yan College, a secondary school in Wan Chai, Senior Superintendent Li Kwai-wah of Organized Crime and Triad Bureau, said at a media briefing.

Bomb disposal officers of the police Explosive Ordnance Disposal Bureau were then deployed to the scene, and found two suspicious objects attached with wires and mobile phones.

After examination, the officers confirmed the two radio-controlled improvised explosive devices were "fully functional and ready to be used," said Senior Bomb Disposal Officer Alick McWhirter.

According to McWhirter, the two devices contained approximately a total of 10 kg of high explosives. The explosives consisted of two different types, a primary high explosive designed to act as the detonator and booster and a secondary high explosive based around ammonium nitrate.

In addition to the large quantities of explosives, shrapnel in the form of nails had also been added to both of the devices.

"Both of these devices have only one function, to kill and to maim people, given the quantities of the explosive and fragmentation," McWhirter said.

"Had these devices functioned, they would have killed and injured large number of people. These were exceptionally dangerous and credible devices," he said, adding that the bombs' killing range could reach 50 to 100 meters.

Li said the police will investigate who placed the bombs inside the school, the perpetrator's motive and target, as well as the incident's connection with recent violent activities.

He said making or possession of explosives is a serious crime liable to imprisonment for 14 years, and using any explosive substance to cause an explosion likely to endanger life or cause serious injury to property is liable to life imprisonment.