POLICE suspect the gang of armed raiders who gunned down four people - killing one young woman - after a $10 million jewellery heist yesterday are professionals who have struck before and will try again. Similarities in the modus operandi of yesterday's holdup of a jewellery shop in Swire House and a raid on a similar store nearby two months ago point to the same gang being responsible, police sources said. In both raids three smartly-dressed robbers wielding pistols and threatening to detonate a grenade forced staff to hand over expensive gold and diamond-studded watches and necklaces. Both times, the bandits struck between 3 pm and 3.30 pm, chose not to wear masks and escaped into crowds. Hong Kong Island Regional Commander Tsang Yam-pui said last night the similarities were being investigated by detectives from the Organised Crime and Triad Bureau. Footage from a security camera, fingerprints and the descriptions of staff terrorised at gunpoint in the Precision Watch Company in Chater Road yesterday are being compared with similar evidence from the March 14 holdup of the Dickson Watch and Jewellery Company across the road in the Landmark. ''We are dealing with an extremely dangerous gang who resorted to the use of extreme violence. Their indiscriminate firing in a very crowded area is nothing but cold-blooded murder,'' said Mr Tsang. Lau Sze-man, 23, who was shot in the head by a 7.62 mm bullet believed to have been fired from a China-made Black Star gun during the gang's getaway through the Landmark, died shortly afterwards. Police Constable Chan Ka-choi, 22, one of four who drew their guns and gave chase as the robbers ran with their cache of 89 watches, eight gold chains and three gold pendants, was shot in the leg near the basement entrance to the Landmark. British woman Tina Noden, 23, who is a waitress in a Lan Kwai Fong bar, underwent surgery last night after being shot in the abdomen and the leg. The fourth victim, Siu Ming-sun, 50, was also shot in the abdomen. The robbers made their getaway by firing indiscriminately as four police officers pursued them amid hundreds of terrified commuters and shoppers shortly after 3.15 pm. Witnesses described the scene as chaotic and terrifying, with people diving for cover in all directions, running into shops, hiding behind pillars and MTR machines. Pandemonium reigned in the heart of Hong Kong as more than 100 police, including flak-jacketed marksmen, converged on the scene and conducted sweeps of nearby buildings while thousands looked on. After one of the constables was shot in the leg, his three colleagues suffered ankle injuries and were unable to continue the chase. ''As they arrived at the entrance of the Landmark, two of the culprits turned around and fired indiscriminately in the direction of the police officers,'' said Mr Tsang. He said the Cantonese-speaking robbers ''went right through the Landmark building itself and were lost in the crowd''. Police believe the robbers might have re-entered the MTR system and caught a train out of Central. ''It was too risky to fire back because it was extremely crowded. You can imagine how many people there are in the Landmark in the middle of the afternoon,'' said Waterfront police divisional commander Superintendent Dave Madoc-Jones. Chaotic scenes unfolded as cameramen and reporters jostled with spectators and even schoolchildren to get a glimpse of the injured. The four police officers were on patrol when an alarm in the jewellery store was tripped by one of the staff, who were showing two Chinese shoppers a selection of watches when the robbers walked in and made their demands. Police said the raid was the most serious since early 1993 when a woman nurse was shot in the head by a gang armed with AK-47 assault rifles while escaping along Nathan Road in a car. Mr Tsang, who visited the injured police and passers-by in Queen Mary Hospital, said no stone would be left unturned in the hunt for the robbers. Police want the two customers who were in the shop during the raid and later fled to come forward. He praised the four pursuing constables for doing all they could under the circumstances and applauded their judgment for not firing at the robbers. ''They exercised maximum restraint and they did the correct thing by not returning fire, otherwise the tragedy could have been much worse,'' he said. ''Regrettably, after three hours of searching we have not been able to arrest any of those responsible for the crime.'' Police believe the criminals were ''stealing to order'' and already have an outlet for the Chopard, Rolex and Tudor brand watches and jewellery which they stuffed into carry bags.