A couple was killed and their grandson injured when a speeding Tamil Nadu bound bus knocked down the motorcycle they were riding on the busy K.R. Market flyover on Tuesday morning. The deceased have been identified as Antony Joseph (55) and his wife Sagai Mary (53). Their minor grandson, who is yet to be identified, was severely injured and has been admitted to Victoria Hospital. The victims were on their way to J.J. Nagar to visit their relatives from Wilson Garden. The driver abandoned the bus and fled the spot soon after the accident. Traffic was disrupted for some time till the Chickpet traffic police rushed to the spot and cleared the accident spot. The police have seized the bus and efforts are on to nab the driver.