2 appliances from the Isle of Wight Fire and Rescue Service are currently in attendance on West Street, near to the junction with Argyll Street.
It has been confirmed that a grill pan caught alight, prompting the double turnout.
It appears that the fire was out upon arrival of the first crew, but positive pressure ventilation is now being utilised to clear lingering smoke from the flat.
The incident began shortly before 17:30.
The road remains open as normal.