They tried to go back, but flooding had inundated the road at Hawks Crag, Ms Hands said.
They waited until the rain eased and the flooding receded, then drove back to Berlins where other motorists told them the road to Inangahua was blocked by two more slips.
"We just parked up at Berlins - there was about eight cars - and just waited and waited."
There was limited cellphone coverage. Nightfall came, and her one-year-old son Lucas dozed off. Ms Hands, her father Mel, who's in his 60s, and Jessica, aged three, couldn't sleep. They had not eaten since lunchtime and had only two muesli bars and some cold drinks in the car.
A Columbian couple in a campervan, who had just avoided ploughing into a slip, came to their rescue with chocolate biscuits, an umbrella and a jacket, and let them use their self-contained toilet, Ms Hands said. "They were great."
About 10 o'clock, lights appeared on the horizon.
Ms Hands flashed her lights as they passed and a Downer vehicle stopped. Behind it was a loader and a police car, looking for a pregnant woman who was not among the motorists at Berlins.
The motorists were told they could proceed with caution towards Westport. It was a scary drive, Ms Hands said.
"The drains were all full and flowing like streams and there were big rocks. The other concern was, you were worried a slip or rocks was going to come down on top of you."
The drive from to Westport took about 50 minutes, she said. "We were doing 50k, we didn't want to go any faster."
The Hands family had been planning to go to Karamea, but SH67 was flooded at the Pines Tavern and they spent the night with relatives in Westport. They planned to complete their trip to Karamea today.
New Zealand Transport Agency spokesman Mark Pinner said several slips came down on the Lower Buller Gorge, SH6 between Inangahua and Westport, between 5pm and 6pm.
"They [motorists] obviously got stopped by one slip then turned around and couldn't get out for the other. Around about 6 o'clock we got the message and it was around 11 o'clock we knew they got out safely."
Mr Pinner said the worst slip was at Nine Mile, where there had been two big slips in recent months, with others at Whitecliffs and Berlins.
The Lower Buller Gorge and SH69, Inangahua to Reefton, reopened around lunchtime today.
Mr Pinner said damaging storms had become almost a New Year occurrence on the West Coast.
On January 13 last year, winds gusting to 100km an hour felled trees, damaged property and cut power in Buller.
On December 28, 2010 the worst floods in a century hit Seddonville and torrential rain caused damage throughout Buller.
