FIREBUGS set fire to three patches of grassland near to a Sunderland estate.
Firefighters from Sunderland Central Fire Station were called to the field near Bunnyhill and Hylton Castle at 7.50pm yesterday, then again at 8.50pm.
The same crew were called out to the plot at 6.30am when another fire was set away.
Firefighters say each of the blazes was started on purpose.
The officers used hose reels and beaters to put out the fires.