Around 30 whales are stranded in an estuary of a sea loch in the Scottish Highlands.
The pilot whales became completely beached as the water in the estuary off Kyle of Durness ebbed away at low tide.
It is feared that some of the whales are already dead.
Earlier on Friday, three pilot whales, including a calf, beached on the shore of the loch.
Rescuers at the scene said the whales were part of a pod of around 60 which got trapped in the loch at one of Britain's most northerly points.
The British Divers Marine Life Rescue charity said the three whales are being given first aid on the beach.
The Navy and Coastguard are also helping with the rescue, which is expected to continue through the night. It is hoped that some whales can be rescued using inflatable pontoons to float them to safety once the water returns.
Charlie Phillips, a Whale and Dolphin Conservation Society field officer, said: "There are now between 25 and 30 whales completely stranded in the sand. The tide is out at the moment so there is very little water in the estuary.
"It is difficult to tell how many have survived. Some appear to be alive, others are moribund and it looks as if some have died.
"We will be able to get a clearer picture when the water comes back."