By Jennifer JettHONG KONG — A major fire tore through multiple high-rise towers at a housing estate in Hong Kong on Wednesday, killing at least four people, officials said.Police received multiple reports of people trapped in the estate, where bamboo scaffolding has been erected outside several towers as they undergo renovation, local media reported. Three others were injured, two of them critically, in the fire at Wang Fuk Court in the northern district of Tai Po, the Fire Services Department said. At least one firefighter was believed to be among the dead, according to local broadcaster RTHK.Firefighters were still battling the blaze several hours later as night fell. Massive flames and thick plumes of dark smoke could be seen coming from multiple towers at the housing complex, which has eight buildings and almost 2,000 residential units. The blaze was classified as a No. 1 alarm fire when it was first reported at 2:51 p.m. local time (1:51 a.m. ET), but it was quickly upgraded to a No. 3 alarm fire at 3:02 p.m. and a No. 4 alarm fire, the second-highest level, at 3:34 p.m., the Fire Services Department said. The Transport Department said a number of bus routes had been diverted and that sections of some nearby roads had been closed to all traffic.Hong Kong has been under a red fire danger warning since Monday, which means there is an extremely high risk of fire. Jennifer JettJennifer Jett is the Asia Digital Editor for NBC News, based in Hong Kong.Peter Guo and Jay Ganglani contributed.