A gang war erupted in Patna City late on Thursday evening, as criminals gunned down gangster Sonu Paswan alias Hullar Paswan on the banks of the Ganga.

Sonu was a close associate of jailed Independent MLC Ritlal Yadav.

A group of six armed criminals attacked Sonu while he was engaged in conversation with three associates at Quila Ghat under the jurisdiction of Chowk police station.

The assailants fired at him from close range, and fled towards Patthar Ghat.

Police said the incident occurred around 7.30pm. Sonu, also known as Shambhu, had recently shifted to Patna City from the Khagaul area after the cops stepped up action against him.

He was living with his brother-in-law Raju Paswan, a resident of Kaimashikoh, Patna City.

The station house officer (SHO) of, Ashok Kumar Pandey, said a motorbike, an empty and one live cartridge were recovered from the spot. Two suspects have been detained for interrogation, Pandey said, adding that raids were on to arrest those involved in the crime.

The murdered gangster was also associated with a controversial building developer, Anil Singh, who is on the radar of the Patna police.

Anil has gone into hiding after a case of land grab was lodged against him with the Gandhi Maidan police station. Sonu also had close connections with contract killer Billu Paswan.

Police sources said at least six cases of murder, extortion, loot and dacoity were lodged against Sonu at Khagaul and Danapur police stations. His criminal antecedents date back to 2001.

"His (Hullar's) murder will lead to a fresh gang war in the capital," an investigating officer said.

Patna City deputy superintendent of police Hari Mohan Shukla, who visited the spot on Thursday, said the incident was a fallout of a gang rivalry. Earlier, his mentor Billu Paswan was killed in an exchange of fire between two groups of people in the Khagaul area, he added.