At least 18 people are dead and more than 170 are injured after a high-speed passenger train derailed in Taiwan’s northeastern Yilan County. the island’s transport ministry says.

The Puyuma express was carrying more than 360 passengers from a suburb of Taipei in the north to Taitung, a city on Taiwan’s southeast coast, when it went off the tracks shortly before 5pm local time on Sunday, the government said in a statement.

Most of the deaths were in the first car, and it was unclear how many people may still be trapped in the train, according to a government spokesman.

The cause of the derailment is still being investigated.

Some passengers were crushed to death, Ministry of National Defence spokesman Chen Chung-chi said.

“Their train car turned over. They were crushed, so they died right away,” he said.

Earlier, the government put the death toll as high as 22, but the National Fire Agency, citing the Cabinet spokesman’s office, later reduced that figure, blaming a miscalculation.

Lu Chieh-shen, deputy chief of the Taiwan Railways Administration, told a news conference that the train was only six years old and had been in “pretty good condition” before the accident.

Photos from the scene just south of the city of Luodong showed the train’s cars in a zig-zag formation near the tracks. Five cars were on their sides.

At least 22 people have died and 171 others were injured after an express train derailed in Taiwan.

This aerial footage shows the scale of the disaster https://t.co/hdtOa2JIff pic.twitter.com/O9cJhWRYII

— ITV News (@itvnews) October 21, 2018

Local television reports said passengers tried to escape through windows and that bystanders gathered to help them before rescuers arrived.

Emergency medical responders and firefighters helped the injured, while the defence ministry said it dispatched 120 soldiers to help with rescue efforts.

Hours after the accident, one of the eight cars was seen tipped over at about a 75-degree angle, with the entire right side destroyed.

Fearing people may be trapped beneath the car, firefighters with lights on their hard hats peered underneath as a crane prepared to upend it. The firefighters were joined by soldiers and Buddhist charity workers who gathered on both sides of the tracks.

Taiwan leader Tsai Ing-wen described the accident as a “major tragedy” on Twitter.

“My thoughts are with all the victims and their families,” she said.

The Puyuma was launched in 2013 to handle the rugged topography of Taiwan’s east coast.

It is distinct from the high-speed rail that runs on the west coast. The Puyuma trains travel up to 150 kilometres per hour, faster than any other in Taiwan except for the high-speed rail.

The train that derailed had its most recent inspection and major maintenance work in 2017, Mr Chie-shen said.

-with AAP