CHENNAI, July 31: A four-member gang on two wheelers opened fire at Luz Avenue, here today, in an attempt to rob Krishnakumar, a passer-by, when they were met with resistance from the public who threw bricks at them. In another incident, a member of a gang snatched the chain of a lady motorist in the busy TTK road, and was aided by an accomplice in escaping. In a third incident, a two-member gang entered a house in West Mambalam and decamped with 25 soveriegns of gold jewellery, after threatening the inmates with a gun. The police have announced a reward of Rs 5,000 to anyone who could give a clue to the identification of the gangs.