SALISBURY — The investigation into an overnight house fire on Mocksville Avenue continues, fire investigators said Thursday.

According to 911 Communications Director Allen Cress, a Salisbury police officer spotted flames sometime before 8 p.m. Wednesday. Multiple fire crews were sent to the scene, 810 Mocksville Ave.

No one was at the home at the time of the fire, and the house was being renovated.

The fire started on a screened porch on the back of the house, said city Fire Marshal Terry Smith. Fire investigators remained at the scene until 11 p.m. and returned Thursday morning for about an hour.

“The fire is still under investigation. We are still following up,” Smith said.

As of Thursday afternoon, investigators had determined no definitive cause.

Although the house was unoccupied, the electricity was on, Smith said.

Responding to the fire were the Salisbury, East Spencer, South Salisbury, Granite Quarry, Locke, Faith, Cleveland and Rockwell City fire departments.

The Ellis, Miller’s Ferry and Landis fire departments provided coverage for the other departments during the fire, according to 911 Communications.

The Salisbury Police Department provided traffic control. Rowan County Rescue Squad and Rowan EMS also responded to the fire.

Firefighters remained at the scene all night through about 9:45 a.m. Thursday to make certain the fire was extinguished.