UPDATE: (7:59 p.m.) — The all clear has been given at the MSU Union. MSU spokesman Dan Olsen confirms the situation arose as the result of an “optical illusion.”

On the roof of the Union is a steam cooling tower. The tower regularly releases steam, as it did this evening. However, Olsen said, the combination of “atmospheric conditions” and a yellow incandescent blub created the illusion that the roof was on fire.

Olsen says the light has been turned out and officials will re-evaluate what sort of light bulb may replace the the current one.

ORIGINAL STORY: MSU UNION EVACUATED

EAST LANSING, Mich. (WLNS) – – The Union Building at Michigan State University was evacuated Wednesday night “out of an abundance of caution.”

MSU Deputy Spokesman Dan Olsen tells 6 News the building had “an excessive release of steam” but no fire. Fire equipment was deployed to the scene and staged in the event a fire was discovered as firefighters cleared the building. Olsen says no fire was found.

Olsen says officials are still determining the cause of the steam release and the Union building will remain shuttered until it is cleared.