The fire – on Lodge Road in Carcroft near Doncaster – involves a two-storey derelict care home with the ground floor well alight.
Fire crews from Adwick, Edlington and Doncaster as well as two engines from West Yorkshire were called at around 3pm today.
People are being asked to avoid the area while firefighters work to extinguish the blaze.
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Fire officers say there are no injuries to report.
More to follow.