JOHANNESBURG, Feb. 1 (Xinhua) -- Three teenagers were killed and 26 others injured on Friday when a footbridge collapsed inside a school in South Africa.

Emergency personnel say that two boys and one girl aged between 14 and 17 died in the incident in Driehoek Hoerskool school in Vanderbijlpark, Gauteng Province.

"When our paramedics arrived at the scene, they found that a walkway connecting two buildings had collapsed," ER24 emergency spokesperson Russel Meiring told Xinhua.

"Rescue services utilized various tools to free the trapped. Four children were airlifted to hospital as they sustained serious injuries," Meiring said, adding that 14 have "moderate" injuries and two are being treated for minor ones.

The exact details of how the structure collapsed remain unclear. An investigation has been launched.