Qld teens safe after disappearing in drain

Six boys feared missing after being spotted walking into a Brisbane stormwater drain have been found safe at school.

The teenagers were seen by a groundsman playing in the drain next to Indooroopilly State High School in Brisbane's inner-west about 8.40am (AEST) on Wednesday.

After an extensive three-hour long search, the students finally told teachers they were the ones who had gone into the drain and had come out at a different end before going to class.

Fears were heightened by significant rainfall overnight which had filled the drains to half full in areas of the elaborate tunnel network, which took hours to search.

Police wouldn't say how old the boys were or which school they were from.

Brisbane regional duty officer Acting Inspector Mark Bradford said the boys' behaviour was extremely risky and could have ended badly as there was a significant amount of water in the drain from heavy rainfall overnight.

Extensive resources were used to search for the missing students in the tunnel system and surrounding area, including dozens of police, paramedics, fire crews and 28 swift water technicians.

Insp Bradford said it appeared other children had gone into the drains in the past and authorities would now consider putting a barrier over the drain entrance.

"It's such a high risk activity that we would plead with everyone to make sure that they don't do that," he said.

Queensland Fire and Emergency Services Superintendent Neil Francis was "dumbfounded" that students would enter storm water drains after significant rainfall.

"It's frustrating for us and we would urge that people not enter any drains," he said.

The Department of Education and Training said strong disciplinary action would be taken against the students.

"The department will always take a tough stance against anyone who does not uphold the core values of safety, respect and responsibility," a spokesperson said in a statement.