SINGAPORE - Adrenaline junkies on the popular Battlestar Galactica roller coaster at Universal Studios Singapore (USS) were stuck on the ride for about 20 minutes on Wednesday (April 6) afternoon after a "technical error" brought it to a halt.

A spokesman for Resorts World Sentosa (RWS), which manages USS, said standard operating procedures were followed to evacuate riders safely from the lower section of the ride.

"The Battlestar Galactica: Human vs Cylon roller coaster experienced a technical error at about 4pm today," the spokesman said.

"The safety of our guests is our top priority and a thorough routine safety check was completed before we resumed the ride at 5.08pm."

He did not say how long riders were stuck on the roller coaster, but a visitor, who wanted to be known only as Mira, said it was for about 20 minutes.

"From what I saw, it took about 20 minutes for everyone to be rescued," she told The Straits Times.

"I was really scared as I myself had been on the ride twice earlier in the day. Now, after seeing this incident, I won't ever go on it again."

Mira, who first alerted citizen journalism website Stomp to the incident, said that USS staff were seen rescuing people one-by-one from the ride, guiding them along the rails to safety.

Touted as the main attraction at USS when it first opened in 2010, the Battlestar Galactica ride has been through some ups and downs.

Barely a week after its opening, a seat fell off the ride during a routine test. No one was hurt, but the ride's licence was suspended immediately.

It subsequently went through 11 months of investigations, redesigning, reassembling and testing.

In July 2013, RWS closed the ride for a review. When it reopened last May, its previous four-seater vehicles had been replaced by two-seater vehicles to allow riders a better view of their surroundings.

Themed after the American science-fiction series about a war between humans and a robot race, the pair of duelling roller coasters climb to around 14 storeys, or 42.7m, at their highest point, travelling at up to 90kmh for 90 seconds.