A video meant to capture a six-year-old boy's roller coaster experience went viral after the ride's seat belt malfunctioned mid-way, forcing his father to hold onto him for the remainder of the ride.

Mr Delbert Latham and his son, Kaysen, were visiting the Wonderland Amusement Park in Amarillo, Texas, on Friday (April 22) when they went on the Mousetrap roller coaster for a second time, local news affiliate KVII reported.

The duo were placed in the same seat as the first time, but when Mr Latham latched on his son's seat belt, it came undone as he tightened the band, he told KVII.

"I just thought I didn't get it clicked in well enough," Mr Latham said. "I re-clicked it and tightened it up. It was fine. There were no problems with it."

On the first drop of the ride, Mr Latham said he felt the seat belt release, and the motion threw Kaysen to the bottom of the cart.

He then grabbed his son and held him for the rest of the ride. He had begun to record Kaysen on the ride for his wife to see, according to KVII.

In the video, which has been shared over 4,000 times on Mr Latham's Facebook page since it was posted on Friday, Kaysen's facial expressions visibly changed from cheery to frightened after he slid to the bottom of the cart.

"I've got you," Mr Latham is overhead telling his son in the video. "You're fine. I promise. There are no more big hills."

Mr Latham said he was not aware he was still filming at that point.

"I was just trying to make sure that he held on and that he didn't start panicking or start trying to move or anything, because I knew that there was another drop coming up," he said.

After being informed of the incident by Mr Latham, an operator apologised to the family and said it had been "happening sometimes", according to KVII.

People were allowed back onto the ride, but not in the cart Mr Latham and his son were sitting in.

"That's when it made me more angry," Mr Latham said, adding that the amusement park should have shut the ride down for safety checks.

In 2014, four people sustained injuries on the same ride, KVII reported, citing a Texas Department of Insurance injury report.

In a media statement, Wonderland Amusement Park said the ride was originally built without seat belts, but they were added in as an extra safety precaution.

"Wonderland immediately reached back out to Mr Latham the evening it happened and promptly removed the back cart from service and ensured all other seat belts were in proper working order. The Mouse Trap was back in full operation on Saturday."

Mr Latham told KVII that he was offered a "couple of WOW passes if I wanted to come back", but he would not be doing so.