At least 27 people are feared dead after heavy rains led to a landslide at a jade mine in northern Myanmar, police said on Wednesday. No bodies have been recovered so far, reported AFP.

The mine is located in Set Mu sub-township of the country’s northernmost state of Kachin. The landslide early on Tuesday buried 27 people, most of whom are from the ethnic Rawang group, said local police officer Aung Zin Kyaw. “We will search again today with the Red Cross and fire brigade,” he said.

Local media quoted witnesses as saying the number of buried was 40. “Nine people are being registered as missing,” Moe Moe, a member of National League for Democracy in Hpakant Township, told Eleven Myanmar. He said that search operations had to be stopped due to the rain.

Rawangs, mainly Christians, are one of Myanmar’s smallest and most impoverished ethnic groups and live mainly in the hilly northern areas. Many of them work in the informal mining sector, which is poorly regulated and riddled with corruption. Working conditions in the sector are dangerous, particularly during the wet months. “Before the rainy season, the people looking for jade were destroying the land,” Shwe Thein, a local resident, told AFP. “Now it is raining and the ground is not stable and very muddy.”

Many people have been killed while mining for jade in the region. On July 14, 22 were killed and 63 injured after a landslide at another mining plot. The source of almost all the world’s jadeite is Myanmar. The country’s multi-billion dollar jade industry has long been shrouded in secrecy amid several complaints of human rights violations.