The cause of a trailer fire in Apache Flats remained unclear Sunday night.

Investigators told ABC 17 News a passerby spotted heavy smoke coming from a mobile home off Business 50 West around 5 p.m. The witness then drove a couple blocks to a nearby fire station and alerted crews there.

When firefighters arrived on scene just west of Jefferson City, there was heavy smoke and flames coming from the trailer.

Smoke could still be seen Sunday night, as firefighters worked to contain hot spots and ventilate the structure.

Jack Brady with Regional West Fire Protection District told ABC 17 News it would be difficult to pinpoint the spark and the cause remained under investigation Sunday night.

The home is considered a total loss, but late Sunday the owners had not yet been contacted.