(KMOV)-- The cause of the 4-alarm fire in an O'Fallon, Missouri apartment complex has been determined.
According to O'Fallon Fire Department, the fire was accidental and caused by a discarded cigarette on a deck.
This broke out at 3:33 Friday afternoon at the Enclave at Winghaven Apartment complex located at 12208 Applerock Drive in O'Fallon, Missouri.
The fire is only in one building, but the building has 16 individual units. The fire apparently started in the second floor and then spread to the third floor and attic. At least six units have been affected, but 3 have been completely destroyed.
The fire was originally called into authorities by a medical unit driving on highway 40, not by a resident of the apartment.
There were no injuries, but about 30 people have been forced out of their apartments.
Dozens of firefighters responded to the scene from departments across St. Louis.