JOHANNESBURG (Reuters) - As many as 25 people are feared dead after a bridge under construction collapsed in South Africa‘s eastern Mpumalanga province, a rescue official said Tuesday. Emergency official Will Lane said the death toll stood at 13, but a further 12 people were thought to be trapped under the rubble of the bridge, which collapsed while under construction over a dam on Monday afternoon. „Site engineers and police are assessing the site this morning. It‘s very unstable,“ Lane said on national radio. „As far as I know, at the scene there are 12 still trapped beneath the rubble and police have been there with sniffer dogs. I can‘t speak on their behalf but it doesn‘t seem likely there will be any more survivors,“ Lane said. The accident occurred when a final section of the bridge was being moved into place, he said. „During this process, something went drastically wrong and the whole structure collapsed.“ Lane said paramedics and police had found 12 bodies at the scene on Monday, with one patient dying in hospital afterwards. Five other people who were badly injured were airlifted to hospital. One, who has severe head injuries, was subsequently ferried to a Johannesburg hospital for more sophisticated treatment, he said. A spokesman for Concor, the construction company, said it was not clear what caused a pillar supporting the bridge to buckle. „We are not sure what happened. We were still constructing the bridge when it collapsed,“ said Concor spokesman Peter Price.