A train derailed near Stonehaven on the east coast of Scotland on Wednesday, according to British Transport Police (BTP). A video clip shared on social media showed a thick black cloud of smoke rising from the site of the accident.

About 30 emergency vehicles, including an air ambulance, are at the scene with more continuing to arrive, local media said.

Scotland's First Minister Nicola Sturgeon on Twitter described the train derailment as "an extremely serious incident."

A number of people have been seriously injured and a major incident has been declared, Sturgeon told the Edinburgh parliament.

"Although details are still emerging I am afraid to say there are early reports of serious injuries," she said.

Local media said torrential rain and thunderstorms on Tuesday have caused flooding and travel disruption across many parts of central and eastern Scotland.

British Prime Minister Boris Johnson reacted on Twitter: "I am saddened to learn of the very serious incident in Aberdeenshire and my thoughts are with all of those affected. My thanks to the emergency services at the scene."

(With input from agencies)