Unidentified gunmen on Saturday attacked a Rashtriya Janata Dal office in Patna killing one person and critically injuring four others sparking off violent protests by party activists who blocked roads, burnt tyres and damaged several vehicles.

Three gunmen opened indiscriminate fire on the Gandhi Nagar office of the RJD candidate for Patna Lok Sabha constituency Ramkripal Yadav. The police said the gunmen escaped in a vehicle, the police said.

Police said factional feud was suspected to be the reason for the attack on the RJD candidate's office, which was opened only yesterday.

The RJD leader is locked in a bitter contest with Union Minister C P Thakur in Patna constituency.

As the news of the attack spread, angry RJD activists took to streets in large numbers, burnt tyres, damaged several vehicles and disrupted vehicular traffic on the new bypass road for several hours.

Hundreds of policemen with anti-riot vehicles were posted in Kankerbagh and Agamkuan locality where tension prevailed after the shootout.

Raids were being conducted at various places to apprehend the gunmen, the police said.

The attack coincided with the visit of Prime Minister Atal Bihari Vajpayee who is scheduled to address a public meeting in the evening.