Hopes of finding three people trapped in a collapsed gold mine in South Africa began to wane on Wednesday, six days after the pillar collapse trapped them.

During the first days of the rescue operation, rescue teams could hear audio signals from the mine. Those signals dropped off for at least 26 hours, dimming hope of finding the employees alive. The International Business Times reported.

The miners are trapped at the Lily Mine near the town of Barberton in South Africa’s northeast Mpumalanga province.

One of the mine’s supporting pillars collapsed Friday, trapping dozens of workers underground. No fatalities were reported, and 87 employees were rescued, but two women and a man who were working in a mobile office container near the mine’s entrance were still stuck. The cave-in created a sinkhole as big as a rugby field that swallowed the container when the gold mine collapsed, mine owner Vantage Goldfields said.

“The three missing are office workers, not miners. We are not going to rest until we find them,” Mike Begg, director of operations at Vantage Goldfields, told Reuters Friday at the mine, which is located about 225 miles east of Johannesburg.

Rescue workers heard tapping sounds Monday from where the missing workers were believed to be trapped, which gave the mine owners “immense hope” that they were still alive, Begg told BBC News. However, rescue teams said the last time they made audio contact was at 1 p.m. local time Tuesday, and there’s been no communication between them since.

Emergency response teams have removed thousands of tons of rock and debris, but Begg said Tuesday they were still between 15 and 12 meters away from the container. The teams will use dynamite to blast heavy rocks blocking their path. Yvonne Mnisi , Pretty Mabuza and Solomon Nyarenda, family members of the trapped workers, have been gathering at the mine with nearby residents in hope of good news, according to South Africa’s Times LIVE.