Four police officers were killed and five people were injured on Saturday when hundreds of Maoist rebels stormed a relief centre in central India set up to shelter those fleeing guerrilla violence, the government said. The rebels attacked the government centre in Dantewada district in the state of Chhattisgarh triggering a fierce gunbattle with security forces for more than an hour, an official said. "The Special Police Officers (killed) were not from the uniformed forces but were surrendered Naxalites (Maoists) appointed by the government to counter their former comrades," state home minister Ramvichar Netam said. The emergency centre was one of 27 the state government has set up to house and protect nearly 50,000 people from Maoist violence. Maoist rebels virtually run parallel administrations in 10 of the state's 16 impoverished districts.