A truck of the civic sanitation department fell into a sinkhole on the premises of the City Post Office in Pune on Friday afternoon. The incident took place around 4 pm in the densely-populated Budhwar Peth locality. The driver of the jetting machine truck -- used to clean drainage lines -- escaped unhurt, said a fire brigade official. Underground work of Pune Metro is going on in the area but the reason for the sinkhole was yet to be ascertained, he added. Videos showed the truck sliding into the pit rear-side first as the surface, paved with interlocking cement blocks, caved in. Efforts to pull out the truck were underway.