NAWABSHAH, Pakistan — At least 28 people were killed Sunday when an express train derailed in southern Pakistan, the railway minister said, with an emergency declared at local hospitals struggling to deal with with dozens of injured.

Accidents and derailments occur frequently on the country's antiquated railway system, which has nearly 7,500 kilometres (4,600 miles) of track and carries more than 80 million passengers a year.

"This is quite a big accident," railway minister Khawaja Saad Rafique told reporters.

"According to the information so far, 28 passengers have been killed and many are injured."

Rafique said at least 1,000 passengers were aboard the Hazara Express when it derailed on a section of track where no faults had been reported.

"There can be two reasons: first that it was a mechanical fault, or the fault was created -- it might be a sabotage. We will investigate it."

The derailment happened near Sahara railway station close to Nawabshah city in the southern Sindh province.

"Eight coaches have derailed," Mohsin Syal, a railway official, told local HUM News.

The railway minister said an emergency had been declared at local hospitals as doctors struggled to treat the injured.

There were chaotic scenes at the Nawabshah Trauma Centre as ambulances and private cars ferried the injured for treatment.

One man leapt from the back of an ambulance clutching a child, his clothes soaked in blood, while a woman moaned in pain as she was carried in on a stretcher.

"We don't know what happened, we were just sitting inside," said one dazed woman.

At the accident site outside Nawabshah, dozens of cars, tractors, rickshaws and motorcycles could be seen parked on a road that runs alongside the track.

Volunteers were wading through a canal that separates the road from the railway line to help, and lifting the injured to get them assistance.

- Relief train -
Some passenger compartments were upright but off the tracks, while others lay on their side, mangled steel from the undercarriage twisted and buckled.

Senior police official Younis Chandio told Geo News from the site that some passengers remained trapped in one carriage.

Ijaz Shah, a provincial railway official, told AFP that a relief train had been dispatched to the site.

The Hazara Express is a daily passenger train that leaves the port city of Karachi in the south and takes around 33 hours to reach Havelian in Khyber Pakhtunkhwa province, some 1,600 kilometres north.

In June 2021 two trains collided near Daharki in Sindh, killing at least 65 people and injuring about 150 others.

In that accident, an express derailed onto the opposite track, and a second passenger train crashed into the wreckage roughly a minute later.

At least 75 passengers burnt to death in a fire aboard the Tezgam express train in October 2019, while a two-train collision at Ghotki killed more than 100 people in 2005.

© Agence France-Presse