Jammu, May 15 (IANS): After a lesser-known terror group claimed the responsibility for the attack on a bus carrying Mata Vaishno Devi shrine pilgrims on May 13 in which four persons were killed and 20 injured, police and the NIA are investigating the incident to ascertain the veracity of the terrorists' claim.

A bus carrying pilgrims of Mata Vaishno Devi shrine had caught fire in Katra area on Friday resulting in the death of four and burn injuries to 20 pilgrims.

A lesser known terror outfit, Jammu and Kashmir freedom fighters (JKFF) later claimed responsibility for the attack saying that the bus had been targeted with an improvised explosive device (IED).

It is not unusual for known terror groups like the LeT and the JeM to carry out attacks and then claim responsibility through outfits which do not exist on ground. A senior police officer told IANS when asked about the veracity of the terrorists' claim.

"We have collected forensic and other evidence. Every possible angle is being looked into. It would be premature to comment on the claim made by this lesser known terrorist group unless we get corroborative evidence."