A wildfire that sparked on the slopes of South Africa’s Table Mountain raged across the University of Cape Town (UCT) on Sunday and into Monday, damaging or destroying a number of historic structures and campus buildings.

Among the most significant losses were the university’s Plant Conservation Unit offices and the Jagger Reading Room, which housed priceless artifacts related to African history, including 19th-century watercolours painted by Indigenous peoples, maps, manuscripts and government records, according to Nature’s Linda Nordling.

Though the fire is now under control, the full extent of the devastation—both to the South African institution and the study of African history—remains unclear.

“We are of course devastated about the loss of our special collection in the library, it’s things that we cannot replace. … It pains us to see what it looks like now in ashes,” UCT Vice Chancellor Mamokgethi Phakeng tells the New York Times’ Christina Goldbaum and Kimon de Greef. “The resources that we had there, the collections that we had in the library were not [just] for us but for the continent.”

The blaze broke out on the lower slopes of nearby Devil’s Peak, a spur of Table Mountain, around 9 a.m. Sunday, rapidly spreading down the mountain to the university campus. Per a UCT statement, about 4,000 students were evacuated from nearby residences and moved to temporary housing.

Authorities are currently investigating the cause of the fire, which was one of several sparked in the area over the weekend. As Odwa Mkentane reports for the Cape Times, authorities are investigating the possibility that an arsonist started at least one of the blazes. Police took a 35-year-old male suspect into custody on Sunday night.

Strong south-easterly winds pushed the fire toward Cape Town’s densely populated neighborhoods, where flames engulfed campus buildings and a hillside restaurant attached to the Rhodes Memorial, which commemorates British colonialist Cecil Rhodes. The blaze also destroyed Mostert’s Mill, a 225-year-old structure that was the country’s oldest working windmill.

More than 200 firefighters and emergency personnel worked to battle the flames alongside four helicopters, reports Lesley Wroughton for the Washington Post. Three firefighters were hospitalized with serious burns, but no other casualties were reported, Cape Town security officials tell the Post. In total, the fire destroyed around 1.5 square miles of land.

The greatest loss may be felt at the Jagger Reading Room, which forms part of the UCT Libraries’ Special Collections and holds many unique and irreplaceable items that tell the story of South African history. Though library directors have yet to assess the scope of the loss, Phakeng confirmed to Cape Talk Radio that the blaze destroyed at least a portion of the Jagger archives’ collections.

“The library is of course our greatest loss,” Phakeng said, as quoted by the Post. “Some of these cannot be replaced by insurance, and that is a sad day for us.”