You can clearly see the fire services are there to assist in the evacuation. Highly unlikely they'd be that quick to respond in an unexpected overrun such as off an unstable approach unless they took all night to evacuate.
AirAsia skidded off the runway | Wee Choo Keong
As you can see from this image, the RFF are in the background assisting in what was a runway excursion, this aircraft veered off the centreline. The decision to conduct an emergency evacuation when there is no imminent danger to the passengers and crew will take several minutes to assess, and the arrival of the RFF can assist in this process.