The Buzzsaw ride at Dreamworld has reopened, after six passengers were left stranded in mid-air on the Gold Coast.

The passengers were stuck in a vertical forward-facing position for about 30 minutes and were unloaded safely from the ride.

A Dreamworld spokesman said the ride was assessed by engineers during Monday afternoon and reopened just before 3pm.

A safety sensor was to blame for the stoppage, after it was triggered and immediately stopped the ride halfway into the vertical climb to the peak.

The most common triggers of a safety sensor are an animal or weather.

"Auto-stopping and resetting of rides is a regular and essential part of operations," Dreamworld said in a statement.

"It occurs for a variety of reasons, from sensor alignment to guest behaviour or weather.

"They are an essential built-in part of ride safety systems and manufacturer's specifications."

The spokesman stressed guests were never in danger because when the sensor was triggered, it stopped the ride in the nearest designated safe spot.

According to Dreamworld's website, the Buzzsaw is one of the 'Big 9 Thrill Rides' and the highest inversion ride experience in the southern hemisphere.

It climbs 15 storeys into the air before sending passengers free-falling through a 360-degree roll and plummeting downwards at speeds of up to 105 kilometres per hour.