A US couple is behind bars and their five children in protective custody after two of them were found blindfolded and bound in a store's parking lot.

Responding to a call from a concerned shopper, Kansas police visited a Walmart store and spotted a five-year-old boy sitting on the ground beside a large SUV with his hands tied behind his back, his legs bound and a blindfold covering his eyes. As an officer approached the car, he noticed a man standing near the vehicle.

"When (the man) saw the officer, he tried to get away from him," Lawrence police spokesman Sergeant Trent McKinley said. The man ducked inside the vehicle and the officer, concerned that the man could be reaching for a weapon, used a stun gun and put him in handcuffs, McKinley said.

A seven-year-old girl was found inside the vehicle, also bound and blindfolded, along with three other children, ages 12, 13 and 15, who were not restrained.

"This is an extremely unusual circumstance," McKinley said.

Officers found the children's mother inside the Walmart and arrested her too, McKinley said.

He said he does not know why the two children were tied up and blindfolded.

The adults were arrested on suspicion of child abuse and child endangerment and were scheduled to appear in court in Lawrence on Thursday afternoon. The 52-year-old father also was accused of obstruction.

The family from Northlake, Illinois, was forced to pull off the Interstate 70 late Monday when their vehicle had transmission problems, McKinley said, citing interviews with the family. They were driving to visit relatives in Arizona, he said.

Walmart is helping the police with the investigation, including providing video surveillance footage, company spokeswoman Ashley Hardie said today.

"We are working closely with the Lawrence police department and providing any information we have," she said.

She would not elaborate on what the video revealed and referred all questions to the police.

- AP