Ten children injured when a concrete pontoon flipped and landed on them at a southeast Queensland dam were swimming after participating in a boot camp.
The incident happened at the Baden Scout Camp at Samford, north of Brisbane, about 6.15pm on Tuesday.
Seven of the children were taken to multiple hospitals for injuries including shoulder dislocations, bruising and as a precaution for spinal injuries, Queensland Ambulance said.
It was initially reported that they were scouts, but a youth boot camp organiser says they were cooling off after finishing an army-style challenge.
Veterans For Youth (V4Y) founder Daimien Patterson praised an 18-year-old lifeguard, who was on-hand for the swimming activity, for ensuring everyone was accounted for.
"We're very fortunate - it could have been a lot worse," Mr Patterson told ABC Radio.
"He even dived under the pontoon to make sure no one was trapped underneath."
Mr Patterson said it was unclear what caused the pontoon to flip but added all children bar one had already returned to training.
"It's not going to deter us from continuing to help these kids," he said.
V4Y will investigate the incident in conjunction with Scouts Queensland.