Seven people were arrested forallegedly killing a 27-year-old man over an old rivalry in suburban Chembur in Mumbai on Tuesday, police said on Wednesday.The victim, Shankar Panwalkar, was attacked with iron rods and sharp weapons by the gang, leaving him grievously injured, an official said, adding that the victim died in hospital.RCF police station senior inspector Sopan Nighot said the prime accused, Pradyuman Yadav, had once teased fiancee of Panwalkar, which led to quarrels between them.Yadav and his six accomplices attacked Panwalkar finding him alone on Tuesday in which he died, he said.A case has been registered under various sections of the Indian Penal Code (IPC) including murder and rioting against all the accused, he said.