HONG KONG, July 6 (CNA) - Hong Kong police on Tuesday (Jul 6) said they arrested nine people on suspicion of engaging in terrorist activity, after uncovering an attempt to make explosives and plant bombs across the city.

Of the nine arrested, six are secondary school students, police said. The group were attempting to make the explosive triacetone triperoxide (TATP) in a homemade laboratory in a hostel.

Police said they planned to use the TATP to bomb courts, cross-harbor tunnels in the city, railways and even planned to put some of these explosives in trash bins on the street “to maximise damage caused to the society".

The nine arrested were between 15 and 39 years of age and are five men and four women, according to Senior Superintendent Li Kwai-wah of the Hong Kong Police National Security Department.

They also included a university management-level employee, a secondary school teacher and an unemployed person, police said.

TATP has been used in attacks by extremists in Israel and London.

Police said the group, called Returning Valiant, had been renting the room at the hostel in the bustling shopping district of Tsim Sha Tsui for about a month.

Officers also froze bank funds of around HK$600,000 (US$77,237.97), as well as cash that they believed was linked to suspected terrorist activities.

"They had a good division of labour among those arrested. Some of them provided money. Some are the scientists - the ones who made the TATP in the room," Li told reporters.

"One is responsible for the sourcing of chemicals and other materials needed for the plan, while another small group of people create the bombs, using chemical equipment. There is also a surveying team and an action team, which is responsible for laying the bombs."

Members of the group had deliberately recruited secondary students who planned to leave Hong Kong for good, Li said.