ISLAMABAD - At least 12 people were killed and 20 others injured Sunday morning as a bus fell into a ravine near Hub, a city some 20 kilometers northwest of Karachi in southern Pakistan, reported local Urdu TV channel Duniya.

According to the report, the accident occurred at about 10:30 am local time when a bus fully packed with an estimated 70 to 80 people on their way back from a three-day pilgrimage fell into a ravine near Hub.

As no hospitals are near the accident site, ambulances had to be called in from Karachi and the ambulances are still on the way, said rescue members on the site, adding that more casualties are expected.

Initial investigation showed that the poor road conditions and the overloading of the bus could be the main culprit for the tragedy.