The death toll from Afghanistan’s worst earthquake in years rose to more than 1,100 on Tuesday, with thousands injured, as challenging terrain hampered rescue efforts in remote villages in the country’s mountainous east, an aid group reported.

At least 1,124 people have died, 3,251 have been injured and over 8,000 houses have been destroyed, said the Afghan Red Crescent Society, a humanitarian group working in the region, adding that more people are feared trapped under rubble.

The U.N. coordinator in Afghanistan said the toll was likely to rise.

Afghanistan is prone to deadly earthquakes, particularly in the Hindu Kush mountain range, where the Indian and Eurasian tectonic plates meet.

The earthquake, with a magnitude of 6, struck around midnight local time Monday, at a shallow depth of 10 km (6 miles), with the eastern provinces of Kunar and Nangarhar being the worst-hit.