Police said on Monday that a remote-controlled improvised explosive device, similar to those used in terrorist attacks in foreign countries, was detonated at Nathan Road on Sunday, saying they believe it was targeted at officers.
At a press conference, deputy police commissioner Tang Ping-keung said they believe the device, planted at the junction of Nathan Road and Fife Street in Mong Kok, was detonated via mobile phone.
Tang said that at the time, a police car had just arrived at the scene to clear a roadblock put up by anti-government protesters.
An officer had just got out of the vehicle when the bomb, which was planted in a flowerbed 10 to 15 metres away, exploded, he said.
The officer described the explosives as similar to those used in some terrorist attacks in other parts of the world and said knowledge and expertise was needed to manufacture these.
Meanwhile Kong Wing-cheung, acting chief superintendent of the police public relations branch, said that a total of 201 people were arrested from Friday to Sunday.
He also said seven people suspected of criminal damage were arrested near a snack shop in Kwai Chung Square and six of them were students.
In addition, 26 people were arrested in Flora Plaza in Fanling on suspicion of damaging a bank and 18 of them were students. Kong warned students not to be misled into thinking such acts are only like carrying out some "decoration", saying they are illegal.