In total eleven passengers were left injured (Picture: Twitter/Samantha Grange)

A bus carrying teenage campers rolled over on a winding Idaho highway Friday afternoon leaving seven people severely injured.

Around 30 campers and staff were being taken back to Boise from the Treasure Valley YMCA’s camp at Horsethief Reservoir.

All of the teens on the bus were between 13 and 18 years old, according to Idaho State Police.

Four others had non-critical injuries.

Hospitals are now ‘working to reunite families,’ said spokesperson Taylor Reeves Marschner.

Treasure Valley YMCA President and CEO David Duro said the Sunday to Friday overnight camp session had just ended and riding the bus is normally a great part of the experience for campers.

‘It’s one of those experiences that every child should be able to enjoy safely and I don’t know what happened,’ he said.

‘All we’ve been told is that it’s under investigation.’

Seven teenagers were left critically injured (Picture: KTVB)

The YMCA camp where children can engage in canoeing, archery, zip-lining and other outdoor activities opened in 2010 and is about 35 miles (56 kilometers) north of the crash site.

‘It’s the first time we’ve ever had something like this and we hope it’s the last time, Mr Duro said about the crash.

He added they’ll be awaiting any reports to review and see what can be done to make the journey safer.

The YMCA contracts Caldwell Transportation to take kids on school buses to and from the camp.

The crash blocked both lanes of Highway 55 for hours. The two-lane road is one of the state’s two major north-south routes.

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‘It’s one of those experiences that every child should be able to enjoy safely and I don’t know what happened.’