Several homes had to be evacuated following the blaze at the disused Glenmac mill at Crown Close after firefighters were called to the scene in the town's Cross Wynd at around 5.20pm on Tuesday, December 7.
Flames licked the side of the building and smoke was seen billowing from it.
Part of the High Street was sealed off while crews brought the fire under control.
It is not known yet if the incident is being treated as suspicious but one eyewitness said children had been seen running from the area.
Today the ramifications of the fire at the building, which closed more than three decades ago, were being considered. There have been a number of reports in the past of youngsters entering and causing damage within the property.
The fire may now increase the possibility of the old mill being demolished.
Hawick provost Watson McAteer had initial concerns over the implications for the town’s Covid-19 vaccination centre, located just yards away, but the facility remains open,
He said: "There was a report on social media with some woman saying she saw three lads running away from the site, but it’s too early to say. I haven’t seen any proposals for its demolition but I suspect this incident may bring that discussion forward.”