The attack camejust three days after a local ex-policeman took a busload of Hong Kongtourists hostage in Manila , killing eight of them before being shotdead by a police sniper.
The bus was travelling fromCagayan de Oro to Zamboanga City in the southern Philippines ,where Muslim rebels and criminal gangs operate, said Orlando Vinas, theLanao del Norte provincial police chief.
The gunmenordered the passengers to get off at a road checkpoint and shot fourpeople, including the two uniformed police marshals, the driver and thebus conductor. They then burnt the bus.
No organisation or individuals have taken responsibility for the attack.
Vinas said that the marshals were deployed on regional buses plyingthe same highway after gunmen held up a bus to extort money frompassengers earlier this month./.