The NI Fire and Rescue Service (NIFRS) said the blaze is believed to have started within a machine at the plant.
The fire, which has now been extinguished, has damaged the roof and machinery but it was "localised to that area of the plant", NIFRS added.
No one was in the area when it caught fire and there are no injuries.
Bombardier Belfast Fire from a Fireman's view. Looks like it's completely gutted pic.twitter.com/DfoiNQTZVF— Connor (@ConnorMonaghan_) May 24, 2020
NIFRS said some firefighters will remain at the scene to observe and monitor for potential hot spots. It said that Bombardier would carry out its own investigation into what happened.
Airport Road, where the factory is situated, has reopened. (end of excerpt)
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