A robot dispatched to peer into the New Zealand coal mine where 29 miners are trapped has broken down inside the mine, and families of the men are "extremely frustrated," police said Tuesday morning.
The military-operated robot was expected to be a key part of the search for any survivors. But Gary Knowles, superintendent of the Tasman Police District, told reporters Tuesday morning that the robot's operators told him the probe had stopped operating.
No one has heard from the men - ages 17 to 62 - since an explosion inside the mine around 4 p.m. Friday.
Officials hope they are alive, though they do not know whether the men found a haven or whether parts or all of the mine collapsed.
The families of the missing men were "extremely frustrated" after a Tuesday morning briefing by authorities, Knowles said, "and I can understand their frustration as to the time it's taken to have a rescue."Â But he said safety was his paramount concern in the rescue attempts.
AÂ potentially explosiveÂ mix of gases inside the coal mine made it too risky for rescue workers to enter, officials said.