Hong Kong / China (13 June). Police say they seized a batch of circuit boards that were of a similar design to those installed in two remote-controlled devices found in December. Whereas Hong Kong Police are achieving some success of shutting down some extremists cell, experts question how many more extremist cells are operating in Hong Kong.
The government announced that seven groups are known to Hong Kong Police but security officials commented no further.
A 20-year-old postsecondary student has been arrested in connection with the manufacture of two powerful home-made bombs that were hidden on a Hong Kong school campus in December, police say.
At the man’s home, officers seized a batch of circuit boards that were of a similar design to those installed in the two remote-controlled devices that contained 10kg (22 pounds) of explosives in total, said Senior Superintendent Steve Li Kwai-wah of the organised crime and triad bureau on Wednesday.
“The function of the circuit board is to receive a mobile phone signal and convert the signal into electrical current,” he said. “Going through a resistor, the current will generate heat that detonates the explosives.”
He said the HMTD, or hexamethylene triperoxide diamine, found in the bombs was the type of explosive that would be detonated by heat or flames.
According to police, investigations revealed a gang of would-be bombers made contact through social media in a conspiracy to manufacture explosives amid months of anti-government protests in the city.
Li said the student was taking a mechanical-related course. “We are still investigating how he learned to make this,” he said.
After a four-month investigation, the suspect was picked up at Sau Mau Ping Estate at about 10pm on Tuesday. In additional to the seizure of circuit boards, officers also found tools for making electronic devices, nails and 150 child pornography pictures and seven such videos.
Police arrested the student on suspicion of conspiracy to wound with intent. On Wednesday afternoon, he was still being held for questioning.
The two bombs, which were connected to mobile phones and each packed with 5kg (11 pounds) of high-grade explosives along with shrapnel in the form of nails, were found hidden inside two black rubbish bags under a building that was supported on pillars at Wah Yan College Hong Kong in Wan Chai on December 9.
Officers believed the devices were intended for an attack on police at a massive anti-government march on December 8 and were temporarily stored on the campus after the would-be bombers were forced to abandon the plan.
During the operation, officers raided three flats in Wan Chai, North Point and Chai Wan, arresting 11 people and seizing weapons including a pistol, 105 bullets, two bulletproof vests and a number of retractable batons.
In October, an explosive device hidden in a flower pot in Mong Kok was detonated shortly after police officers moved in to clear roadblocks set up by protesters nearby. No officers were injured in that explosion.
In January, police arrested 10 members of a radical anti-government group in a series of raids and seized a pipe bomb – the first such improvised explosive device in the city – from a subdivided flat in Mong Kok.