Hong Kong police have arrested six men in connection with the theft of 70 luxury watches worth about HK$13 million (US$1.7 million) from a store in a major shopping district last week.

Chief Inspector Cheung Ka-wing, of the Hong Kong Island regional crime unit, on Monday said four of the suspects, all unemployed and aged 20 to 35, were arrested in Causeway Bay and Mong Kok on Sunday.

The force had been searching for a gang of four robbers who raided Tse’s Collection, a ground-floor shop at the junction of Lockhart Road and Canal Road East in Causeway Bay, at about 1pm on Wednesday.

Security footage from the scene showed three of the group armed with a hammer, a knife and what appeared to be a pistol, which were used to threaten staff into giving up the key to the store’s display cases.

Some 36 of the 70 stolen watches, which included brands such as Rolex and Audemars Piguet, were recovered from hotel rooms and residences where the four suspects were staying, alongside HK$230,000 in cash, he said.

“We’re now looking for other stolen watches and will not rule out the possibility of more arrests,” Cheung said, adding that his team was investigating whether the gang was involved in any other crimes.

According to the force, investigators believed the cash seized during the arrests were crime proceeds, but they had not determined if they were connected to the sales of the stolen watches.

Police had earlier suspected that the gang had escaped from the scene by jumping into a black getaway car on Jaffe Road, but the chief inspector said the robbers had used two vehicles.

The owners of the two cars, aged 32 and 43, were arrested in Yuen Long and Happy Valley for their alleged role in the robbery, the force said, with the pair suspected of loaning the cars to the gang with full knowledge of their intended purpose.

Cheung said officers had not located the possible firearm used during the raid, but added there was no evidence to suggest a real pistol had been used.

Police said the gang were observed strolling around Causeway Bay and Wan Chai on Wednesday morning, with the members potentially scouting the area surrounding the store in preparation for the heist.

All six of the suspects, some of whom were believed to be triad gang members, were being held for questioning as of Monday evening.

The chief inspector appealed to the public to contact the force at 2860 7834 or 9886 0043 if they came across any watches of an unknown origin or suspected stolen items.