Four labourers died and at least 40 others were injured on Tuesday when the tyre of a pick-up van they were travelling in burst and the vehicle overturned near here, police said.The injured have been rushed to hospitals in Badnagar and Ujjain city.Badnagar Poli Station in-charge Vivek Kanodia told IANS: "A contractor's pick-up van was ferrying labourers from Bilgaon in the morning when the tyre burst and the vehicle fell into a roadside ditch."Three labourers died on the spot, while another succumbed to his injuries in hospital."More than 40 labourers were injured in the accident. The severely injured labourers have been referred to a Ujjain hospital," Kanodia said.