Ghaziabad, Nov 19 (IANS): Three people were killed and four injured when unidentified gunmen opened fire at a rival gang leader who was attending a marriage function here Friday night, police said Saturday.

Sundar Bhati, who is named in a number of criminal cases in Greater Noida, was attending the marriage function of his niece Neelam Singh at a guest house in Sahibabad, when suddenly a group of men barged in and started firing at him.

Police said the attack was led by Amit Kasana, the nephew of Naresh Bhati, a former chairman of Gautam Budh Nagar district panchayat, who was allegedly killed by the Sundar Bhati gang in 2003.

Sundar Bhati and his men then retaliated, taking the cover of furniture at the venue.

The firing left three dead -- a private gunner of Sundar Bhati identified as Shokeen, Bhati's nephew Naveen and Jabar Singh, a member of the Amit Kasana gang.

The four injured were rushed to hospital.

Both the groups later fled the spot.

Assistant Superintendent of Police Amit Verma said: "The police have recovered 30 used cartridges of different calibers, including prohibited bore 9 mm. The use of AK-47 is also being investigated."

"Sundar Bhati is a known criminal of Greater Noida area, having over two dozen criminal cases in police stations of Greater Noida, Noida, Bulandshahr, Ghaziabad and Faridabad. Amit Kasana is also an active criminal in Greater Noida," he added.

While no arrests have been made, seven people have been detained for questioning.