The accident took place when the Maruti Zen car driven by retired engineer S.F. Fatami crushed a group of labourers who were cooking their food on the pavement near Shankar crossing in posh Gomti Nagar locality.

"It's a tragic incident. Preliminary investigations indicate it took place after the driver suffered heart attack," Deputy Superintendent of Police Gyananjay Singh told reporters here.

"While two labourers died on the spot, four received critical injuries. The four injured labourers and the retired engineer have been admitted to a hospital," he added.

"The condition of the retired engineer and the four labourers is stated to be serious," he added.