The death toll resulting from a collision involving a bus and an oil tanker in Karachi, Pakistan, climbed to 63 Sunday, with some bodies being described as unrecognizable. Witnesses said an oil tanker was speeding on the wrong side of the road when it collided Saturday with an oncoming bus. Some traveling on the roof were able to jump to safety, but many inside were trapped as both vehicles burst into flames.

"The bus carrying some 50 passengers hit the oil tanker, which, according to initial reports, was coming in a wrong direction," senior police official Rao Muhammad Anwaar told AFP.

The bus was en route to Shikarpur when the incident occurred about 30 miles from Karachi.

Police said the driver of the tanker fled the scene and is being sought for questioning. "We are trying to ascertain if the driver of the oil tanker was solely at fault or whether the bus driver also showed negligence," Anwaar said.

The BBC reported 57 bodies were taken to Jinnah Hospital in Karachi, where head of the Emergency Department Dr. Seemi Jamali said the death toll may rise. The bodies were later taken to Edhi morgue.

Pakistan sees more than 9,000 crashes on its roads every year, with around 4,500 resulting fatalities, the BBC reported. 

The accident comes just two months after more than 50 people died when a bus collided with a goods vehicle near the city Khairpur, in the north of Sindh province.