<p><br /> Gunmen wearing police uniforms have stopped a passenger bus in the Philippines and shot dead four people.<br /> </p><p><br /> The attack came just three days after a disgruntled ex-policeman took a busload of Hong Kong tourists hostage in Manila, killing eight of them before he was shot dead by a police sniper.<br /> </p><p><br /> Police said the bus attacked on Thursday was travelling from Cagayan de Oro to Zamboanga city in the southern Philippines, where Muslim rebels and criminal gangs operate, when it was flagged down at a road checkpoint by gunmen in police uniforms.<br /> </p><p><br /> They ordered the passengers to get off and then fatally shot four people, including two uniformed police marshals, the driver and the bus conductor, said Orlando Vinas, the Lanao del Norte provincial police chief.<br /> </p><p><br /> The attackers set the bus on fire and fled.<br /> </p><p><br /> "We have information that the motive has been revenge by lawless elements against the bus management," Vinas said.<br /> </p><p><br /> Vinas said the marshals were deployed on regional buses plying the same highway after gunmen early this month held up a bus to extort money from passengers.<br /> </p><p><br /> Highway robberies are common in the country's south, where the proliferation of illegal firearms and weak law enforcement have fuelled the Muslim separatist insurgency and instability for decades.<br /> </p>
