Twenty-six people were injured on Saturday morning when a double-decker bus crashed into a railway bridge in London, slicing its roof off, the Fire Brigade said.

Three people who were trapped on the top deck had to be freed and five were taken to hospital after the pre-dawn collision in Tottenham, North London.

"Two fire engines, a fire rescue unit and 15 firefighters were called to a collision involving a bus and a railway bridge on St Lays Road in Tottenham early this morning," the brigade said in a statement.

Police said they were investigating the incident and that none of the injured was in a life-threatening condition.

Transport for London (TfL) said the bus had been privately hired, and was not operated by TfL. But a spokesman was unable to comment on media reports that the bus was being operated by an events and entertainment company.