Hospital workers carry in the first victims of an oil tanker explosion in Bahawalpur at Nishtar hospital in Multan, Pakistan, on June 25, 2017. [Photo/Agencies]

ISLAMABAD - The deadly oil tanker fire that claimed at least 123 lives and wounded over 100 others in Pakistan's eastern Punjab province on Sunday morning could be caused by smoking, said police.

Imran Shah, spokesman of Pakistan Motorway Police, a top body in charge of the security issues of motors in the country, said that initial investigation suggested that the fire broke out after someone on the spot lit a cigarette.

Further probe into the incident is still underway, he said.

Earlier on Sunday morning, a fully packed oil tanker skidded off the road after tire burst on a highway in Ahmad Pur Shaqia, a small town lying about 400 km southwest of Lahore, capital city of Punjab province.

The fire broke out after many people from nearby villages came in motorbikes to collect the oil spilled out from the capsized oil tanker, said eyewitnesses.

A total of 75 motorbikes and six vehicles including a traffic police vehicle were burnt out in the fire, said police. The site is littered with numerous bodies burned beyond recognition, said eyewitnesses.

Three fire engines rushed to the site following the report of the oil tanker fire which broke out at about 6:23 am local time, said fire engine department officials, adding that it took them hours to have the fire put off.

Several helicopters have been dispatched to the site for rescue work, said Inter-Service Public Relations, a media wing of Pakistan Army, in a statement.

Due to the lack of doctors and facilities for burn injuries, many of the seriously burned have been shifted to hospitals in the nearby cities of Bahawalpur and Multan.

Muhammad Baqir, an official in charge of the rescue work, said that 123 people were killed in the fire while over 100 others suffered from burn injuries to different degrees.

Dr. Aurangzeb, Medical Superintendent of Victoria Hospital in Bahawalpur, a district which Ahmad Pur Shaqia falls under jurisdiction, confirmed that 120 bodies and over 100 injured people have been received by different hospitals in the district.

The death toll could further rise as 31 injured people are in critical condition, he said.

Latest reports coming in said that the death toll from the oil tanker fire has risen to 140, but the figure is not officially confirmed.

Both Pakistani President Mamnoon Hussain and Prime Minister Nawaz Sharif have expressed deep sorrows over the loss of so many precious lives in the incident.

Sharif, who is currently abroad on a private trip, instructed all the concerned authorities to provide the best available medical treatment for the fire victims.