The crane was being used to build a bridge for the upcoming high-speed rail line between Bangkok and China, via Laos. However, the train that was hit was traveling on existing tracks from the capital to Ubon Ratchathani on the eastern border with Laos.
Local police chief Thatchapon Chinnawong told AFP that in addition to the fatalities, around 80 people were injured in the accident. Transport Minister Phiphat Ratchakitprakarn said there were 150 people on board the express train.
"A crane fell onto a train, causing it to derail and catch fire," local authorities wrote in a statement.
The fire should now be under control.
The first part of the new high-speed line is due to open in 2028. It is seen as an important link between China and the Southeast Asian countries of Thailand, Malaysia and Singapore.
