The incident occurred around 1 am when the car was going to Dharchula from Tawaghat, SDM (Dharchula) Rajkumar Pandey said.
The victims were residents of Dharchula's Jumna village, he said, adding that the injured have been hospitalised.
"The sudden fall of the boulder could have been caused by the incessant rains lashing the area for the last 24 hours," he said.
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