Duke University said an unknown liquid was mistakenly poured into an air vent.
That prompted officials to make emergency calls, requesting fire and hazmat teams to investigate.
Chopper 11 arrived at the scene to see multiple fire trucks and other emergency response vehicles parked outside the chapel. Firefighters, decked out in all their gear, were then seen entering the front doors of the iconic building.
The investigation confirmed there was no threat to the public and the chapel reopened.