A football pavilion burnt down in Stanmer Park early this morning.
Dozens of drivers raised the alarm as they drove along the A27 at about 5.30am.
Their quick response was praised by East Sussex Fire and Rescue Service which sent three crews from Preston Circus and Roedean to tackle the blaze.
Initial reports suggested that trees were on fire but as fire crews drew closer they saw it was one of the two football pavilions, close to the main road.
Firefighters were there for two hours bringing under control the flames that had engulfed the building.
Crew manager Dave Apps said: “We struggled for water due to its location and we had to set up a relay with the appliances to ensure a constant supply of water.
“We used two foam jets to knock back the flames and then transferred to using hose reels but the whole building was left gutted by the fire.
“Thank you to the public for being so vigilant and for calling in – particularly all those drivers along the A27 who saw the flames.
“They would have seen a huge fire ball and to them it would have appeared as if the trees were alight as they would have been unable to see the building on the other side of the trees.”
An investigation into the cause of the fire is under way.