India, July 4 -- At least 40 people, including women and children, were killed when a bus they were travelling in fell into a ravine in northwest Pakistan's Khyber Pakhtunkhwa on Friday, officials said.

The Peshawar-bound bus departed from Quetta in Balochistan. The accident took place after it reached Dera Ismail Khan district in Khyber Pakhtunkhwa province, officials said.

Preliminary investigation suggests that the brakes of the bus failed, causing the driver to lose control while navigating a difficult bend on the mountainous terrain. The bus skid off the road and fell into the ravine.

However, an investigation has been initiated to further examine the cause, officials said. "According to initial reports, 40 people have been killed...