A father and his son were confronted by armed police after a young boy was seen playing with a toy gun in a car.
Police said they had to respond seriously to reports
Kevin and Jason Price were ordered out of the car and onto their knees after police were told a weapon was seen pointing from the window.
But in fact it was a £15 plastic ball bearing rifle bought for Mr Price's seven-year-old son Connor, who was sitting in the back.
Police have defended their actions, and say they have to treat reports of firearms seriously.
The drama happened when the family from Merthyr Tydfil, south Wales, was travelling home from a bank holiday weekend to Blackpool.
They were travelling in two cars, with the first containing Mr Price and his three sons, Jason, Connor and Keiron, 13.
Mr Price's partner Paula Jones, her son Liam, 11 and her mother-in-law Jennifer Price were in the other car.
Miss Jones explained: "We hadn't gone very far, about 15 to 20 minutes.
"We saw lots of police cars and then there was a helicopter.
The family had been on a bank holiday break in Blackpool
"I was trying to keep up with Kevin and Jason but the police were telling me to keep back.
"I didn't understand why they wouldn't let me get up to Kevin.
"Then we were going on to the M6 and police cars started coming from
"They came in front of us and stopped the traffic and pulled Jason and Kevin in.
"We could see Kevin and Jason getting out of the car.
"They had to get on their hands and knees and were told if they made any sudden movement they would be shot.
"The police put Keiron and Connor in the police car.
"It was a nightmare - Connor was screaming.
"The children were watching their fathers have guns pointed at them," she added.
She said that after officers searched the car, the traffic was allowed to start moving.
"Every time we go on holiday we buy the children a present to come home,"
"They wanted these guns. Liam's was still in the box, but Connor was playing with his.
"Children do play with new toys. He was curious."
"Jason and Kevin could have been shot if they had moved an inch, over a plastic gun," she added.
A spokeswoman for Lancashire Police confirmed that an armed response vehicle had stopped the family's car.
"A ball bearing rifle was recovered from the vehicle and advice was given to the occupants about their behaviour," she said.
"We have to take any reports of firearms seriously."