Explosion in Madison, WI condo building injures at least 4

MADISON, Wis. (WLS) -- At least four people were injured in a condo building explosion in Madison, Wis., Tuesday.

Officials said the explosion happened at the Windsor condominiums shortly before 6 p.m.

One person was taken by ambulance to the hospital while three others took themselves for treatment. The extent of their injuries were not known.

At least six units are affected, but there are no reports of people missing.

Fire officials said that they received reports of an explosion, but when they arrived there was no fire at the scene.

The cause of the explosion is still under investigation.