Malaysian firefighters fought a desperate battle with the fires raging across Sumatra and Kalimantan over 25 days, and faced insurmountable obstacles. At the peak of massive forest and land fires, the numbers of hotspots reached 37,938, which occurred in August 1997.[5] Healthy-looking trees could fall upon them as it base burned out. Peat fires posed the worst risk as the firefighters could be dropped in fire pits as the fires burn deep underground.