Hong Kong Police Wanchai district headquarters, Aug 21, 2019 Photo: Xinhua

The Hong Kong Police Force (HKPF) on Monday arrested another five suspects who were involved in planning bomb attacks in the city after nine had been detained. 

The suspects, four men and one woman, are aged between 15 and 37. They were arrested on suspicion of conspiracy to commit terrorist acts, which breaks the Article 24 of the national security law for Hong Kong, the HKPF told the Global Times on Monday.

The police searched the suspects' houses and working places, pursuant to court warrants, during the operation and seized a number of items suspected of being related to the case. The arrested are now detained for investigation. 

Investigation is still in progress and more people could be arrested, police said. 

Two of the suspects are reportedly "sponsors" of the attack plan, while two others are believed to have helped buy materials and plant the bombs. Three of them were students, according to HK01. 

The bomb attack, described as "terrorist activity" by Hong Kong police, was planned by a local secessionist organization called "Returning Valiant." The group reportedly sought to "recruit" some secondary school students who were brainwashed by extremists and enticed them to act as "death soldiers" for the bomb attack. 

Nine suspects involved in the terrorist activity were already arrested on July 5.

They made bombs in a hostel and planned to bomb courts, cross-harbor tunnels and railways and even planned to put some of these explosives in trash bins on the street to "maximize damage caused to the society," said the HKPF on July 6. 

The "Returning Valiant" became active in earlier 2021 and the police launched an investigation in May, according to Senior Superintendent of Hong Kong police Steve Li Kwai-wah. 

Fan Peng, a research fellow at the Chinese Academy of Social Sciences' Institute of Political Sciences in Beijing, said that the group has a clear division of labor and is organized through a virtual social platform. The impact of such potential connected criminal networks on society will persist for some time, which is alarming. 

"Hong Kong's radicalism and its scourge on young people has not been completely eradicated," he said.

Chief Executive of the Hong Kong Special Administrative Region Carrie Lam noted that the implementation of the national security law for Hong Kong has effectively stopped violence and chaos in the past year, yet there is still a shadow of black violence in the city.