GUWAHATI, India - A bomb exploded under a packed passenger train in India's troubled northeast early on Thursday, killing at least five people, officials said.

Four people were injured in the blast that ripped through the luggage van of the Rajdhani Express travelling to New Delhi from Assam state, a railway official said.

Police suspect the hand of the United Liberation Front of Asom (ULFA) which is fighting for an independent homeland for the 26 million people in the tea-and oil-rich state.

Officials said the train had resumed its journey after the damaged luggage van was removed.