Rescuers are racing to reach seven people who have been trapped in a cave in central Laos since last week.

A group of villagers in Xaisomboun province went into the cave to look for gold on May 19, but heavy rain triggered flash flooding that blocked the exit, according to Laos and Thai rescue teams involved in the operation.

Bounkham Luanglath, who leads the Laos’ Rescue Volunteer for People, told The Associated Press on Monday that one of the people from the group escaped before the exit was blocked and alerted authorities. The status of the seven people who are trapped remains unknown.

He said the cave was a narrow chamber often visited by villagers searching for gold deposits.

Authorities had repeatedly warned people against entering the cave out of safety concerns.

State-run Lao National Radio reported that Thai rescuers arrived at the site on Sunday for assistance.

Divers have since begun navigating flooded sections of the cave toward the area where they believe the group may be trapped.

The Laos’ Ministry of Foreign Affairs declined to comment.

The South-East Asian nation is a one-party communist state with no organised opposition and the government often keeps a tight lid on information.