The accident occurred above central Turkey's Cappadocia region, when an ascending balloon struck another balloon's wicker basket above it, causing a tear in the balloon's fabric and sending it plunging to the ground.
The accident -- the second fatal one in Cappadocia since operations began more than a decade ago -- has put the spotlight on balloon safety and Turkey's civil aviation agency said it had launched an inquiry into the accident. As the tours become increasingly popular, there are questions as to whether too many balloons may be launching over Cappadocia at the same time. In 2009, a British tourist was killed and nine other people were injured when two balloons also collided.
The passengers on board the balloon that crashed were mostly tourists from Brazil, Argentina and Spain, according to Abdurrahman Savas, the governor of Nevsehir province. Many had fractured bones and were being treated in hospital around Nevsehir.
A Canada-based American tourist who witnessed the accident from another balloon, said and the crash occurred some 45 minutes after as many as 100 balloons had taken off for the early morning tour.
"We could hear the radio chatter and we knew something was happening. There was a frantic urgent transmission: `Release your parachute! Release your parachute!" said Ross, whose balloon was some 200 meters (yards) away from the vessel that crashed.
"It was probably some 300 meters in the air and it descended increasingly rapidly to the ground," he said in a telephone interview. "There was a large tear in the fabric, probably some 10 to 15 meters long."
As his balloon flew directly over the crash site, Ross said he saw one person lying on the ground while other passengers were still inside the basket. Several ambulances and trucks were converging on to the scene.
Ross, a professor at University of British Columbia in Vancouver, said that he and his wife had commented before the accident that some of the balloons were travelling "quite close to each other."
Halil Uluer, owner of Anatolian Balloons which operated the tour, told the state-run Anadolu Agency that it appeared that one of the tourists had died of a heart attack. Savas, the governor, said the second person died in hospital. They were aged 71 and 65, Anadolu said.
The balloons were flying above scenic canyons and volcanic cones of the Cappadocia region, a popular tourist destination some 300 kilometers (190 miles) from the capital, Ankara. Cappadocia is famed for its "fairy chimney" volcanic cones and its subterranean cities carved out of soft stone.
In February, a balloon caught fire and crashed in Egypt, killing 19 tourists.
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