A massive explosion has been seen at a university building in Lyon, France.

Footage of the blast shows a fireball erupting into the sky above the building where a smaller fire could already be seen on the roof.

Local reports say the building on the La Doua campus in Villeurbanne, north of Lyon city centre, is a science library.

The area has been evacuated and firefighters are on the scene.

Police told Reuters work was being done on the roof and that a gas bottle exploded, starting the blaze.
At least three people have been slightly injured.