More than 2,000 people could be buried alive by a massive landslide in Papua New Guinea last week, the government said on Monday, as treacherous terrain and the difficulty of getting aid to the site raises the risk that few survivors will be found.

The National Disaster Centre raised the number suspected buried to 2,000 in a letter to the U.N. released on Monday but dated Sunday.

A separate U.N. agency put the possible death toll much lower, at more than 670 people.

The variance reflects the remote site and the difficulty getting an accurate population estimate. PNG’s last credible census was in 2000 and many people live in isolated mountainous villages.

The landslide crashed through Yambali village in the country’s north at around 3 a.m. on Friday while most of the community slept.

More than 150 houses were buried beneath debris almost two stories high. Rescuers told local media they heard screams from beneath the earth.

“I have 18 of my family members being buried under the debris and soil that I am standing on, and a lot more family members in the village I cannot count,” resident Evit Kambu told Reuters. “But I cannot retrieve the bodies so I am standing here helplessly.”

Heavy equipment and aid has been slow to arrive due to the remote location while tribal warfare nearby has forced aid workers to travel in convoys escorted by soldiers and return to the provincial capital, roughly 60 km away, at night.

The first excavator only reached the site late on Sunday, according to a U.N. official. Six bodies have been retrieved so far.

Contact with other parts of the country is difficult due to patchy reception and limited electricity at the site, Reuters reported.

Even when rescue teams can get to the site, rain, unstable ground and flowing water is making it extremely dangerous for residents and rescue teams to clear debris, according to Serhan Aktoprak, the chief of the U.N. migration agency’s mission in PNG.