Six people, including at least three children, have been taken to hospital following an incident on a swing ride at a funfair in Carrickfergus, County Antrim.
Their injuries are not believed to be life-threatening, the ambulance service said.
Emergency services were called to the scene shortly before 18:00 BST on Saturday.
A passenger on the ride told BBC News NI it was a "terrifying experience".
Those injured were taken to the Royal Belfast Hospital for Sick Children, the Royal Victoria Hospital, and Antrim Area Hospital.
A number of other patients were also discharged at the scene.
Lee Toner, 29, who was on the ride with his partner when the incident happened, said the swings had started to knock into each other, and hit parts of the ride.
"As it took off, it started hitting the boards on the outside, and hitting the lights," he said.
"I was having to use my legs to push off the cart in front of me, the cart my partner was in was going into the back of me, going into the side boards as well."
Four emergency ambulance crews, a rapid response vehicle, an ambulance and air ambulance attended the incident.
Three fire appliances, a specialist rescue team and the Red Cross also attended.
It is understood the incident happened when the swings were close to the ground.
A spokesperson for Planet Fun, which operates the funfair, said emergency procedures were taken after an incident on its ride, and at no stage did the ride collapse.
"We immediately sought assistance from the NI Ambulance Service," the spokesperson said.
"We have also reported the incident to the HSE and will co-operate fully with the agency to understand exactly what happened.
"Health and safety is central to all operations at Planet Fun and will offer whatever assistance is required to those customers affected."
Planet Fun said it would make no further comment until the HSE has completed its investigation.
Writing on social media, Health Minister Robin Swann said his thoughts were "with all who have been injured and affected by this incident".
"I wish everyone a speedy recovery and I want to sincerely thank the ambulance, paramedics and fire crews that responded so rapidly to what could have been something more tragic," he said.
The main Belfast Road was closed for a period of time??but has now re-opened to traffic.
Cheryl Johnston, a DUP councillor for the area said parents were "extremely worried" about the incident.
"There are young children, there are families. It is just awful," she said.
"So just hopefully everybody recovers. It's something I know we all didn't expect tonight, and I hope everybody can rally around."
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