KARACHI, Dec 29: A powerful explosion inside an inter-city bus near Karachi’s Cantonment Railway Station on Saturday killed at least six people and left at least 50 others, including women and children, injured.

Although police refrained from calling it an act of terrorism, they were also unable to find credible signs to declare the blast an accident.

Officials and witnesses said the huge explosion ripped through the 70-seat bus just a few metres from the entrance of the station at around 3.15pm. The blast, which was heard miles away, left the bus (ND-2888) in a blaze, with its roof torn apart.

It caused panic in the congested neighbourhood that houses a number of roadside restaurants, eateries and low-fare hotels and is not very far from the Army House.

Several injured people were found lying on the ground before being taken to the nearby Jinnah Postgraduate Medical Centre (JPMC).

“We received six bodies and nearly 50 injured,” Dr Seemin Jamali, the official in charge of the emergency and accident department of the hospital, said. “The condition of some of the injured was critical and they were immediately taken to operation theatres. They all received mostly burn wounds. We have not seen any injury caused by ball bearings.”

The bus was due to leave for Sargodha, but had only three people in it, including the driver, and officials believed most of the victims were outside the vehicle.

The transport company which owned the bus said there was no CNG cylinder installed and also ruled out the presence of any other flammable item inside the vehicle that could have caused the blast.

“It was a diesel engine bus,” Mohammad Rafiq, the bus mechanic and employee of the company, told reporters outside the JPMC, where he was looking for the driver and another staff member who were missing after the incident. “It only carried crates of vegetables and fish. The blast hit the rear end of the bus and we are unable to understand the reason.”

Sindh Information Minister Sharjeel Inam Memon said at the place where the explosion had taken place that it was too early to give the cause of the blast. “Let police investigators and bomb disposal squad complete their work before reaching any conclusion,” he said.

Sindh police chief Fayyaz Ahmed Leghari set up a fact-finding team, headed by the Karachi South DIG, after the “bomb disposal unit found no traces of explosives”.

Police spokesman SSP Imran Shaukat said: “So far we have not found any traces of an explosive because of which we may term it an act of terrorism. There are other possibilities as well, including storage of extra fuel in canisters which are usually placed in a bus.”