Richmond Fire Department responded to Eastern Kentucky University's Grand Campus building number two late Monday morning after a fire alarm sounded.
While in route, RFD Battalion Chief Sam Kirby said firefighters were notified that smoke was in the apartment.
On scene, three occupants waved the firemen in from a porch area. The room, Kirby said, was full of smoke. Crews entered and found a water heater electric box to be the smoking source.
No flames were visible, but emanated as the plastic on the unit heated up, said Corey Lewis, RFD public information officer.