Indian police suspect a blast in a packed train which killed 13 people and left dozens wounded was caused by high explosives.
Indian railway officials had earlier suggested the explosion late yesterday when the train was near Jaunpur in northern Uttar Pradesh state may have been caused by a cooking gas cylinder, sometimes carried by villagers on trains.
But Jaunpur police inspector general Devraj Nagar said they were investigating whether the blast was the work of militants.
"The nature of the blasts suggests the use of RDX explosive," he said. "A terrorist hand cannot be ruled out," he said but didn't give any details.
NDTV television channel said that bomb experts had found traces of RDX in the train.
The RDX high explosive - also known as hexogen - has been used by militants fighting Indian rule in disputed Kashmir and in the northeast region. The rebels have frequently targetted trains in the past.
Thursday's blast took place in the toilet of a crowded carriage, ripping a hole in the floor and damaging the roof, witnesses said. The death toll from the blast stood at 13 after three died in hospital overnight, and another 46 were wounded.
A railway official said some people were injured when they jumped off the train in panic after the explosion.