One of the people is understood to be critically injured, reported the France Bleu channel.
The blast went off at around 9.15am on Friday in what appears to have been a residential building in Dijon in central France.
The building is not far from the central train station, noted France Bleu.
Local mayor François Rebsamen said it was an "extremely violent" explosion, but added that it had nothing to do with an attack.
The local government office said it was a gas explosion.
Firefighters at the scene evacuated the building immediately.