A British woman was seriously injured when a double-decker tour bus that took a detour due to a major display of sporting events got stuck inside a tunnel under a Paris bridge, authorities said.

Three other people were slightly injured, including the husband of the British woman and two Chinese nationals, said Captain Estelle Katsanis, a spokeswoman for Paris firefighters.

The British woman, who was taken to a Paris hospital, was on the open upper deck when the double-decker bus struck the top of the tunnel, Ms Katsanis said.

The scene of the crashThe scene of the crash (Thibault Camus/AP)

Firefighters had to cut away part of the bus to extricate her. Two dozen passengers were on the bus when the accident occurred, Ms Katsanis said.

Dozens of police officers were seen around the bus as it backed out of the tunnel several hours after the accident.

Its top-level windshield appeared smashed and what looked like a tent roof was collapsed.

The accident occurred shortly after noon on Friday as the Big Bus Paris bus travelled from the Place de la Concorde, a large square between the Tuileries Gardens and the Champs- Elysees, the police headquarters press office said.

Police at the sceneFour people were injured (Thibault Camus/AP)

The Big Bus Paris company said the bus had taken the tunnel on a roadway under the Alexandre III bridge, which spans the Seine River, because other routes were closed as Paris shows off its sporting ways in its bid to host the 2024 Olympic Games.

Big Bus Paris operates sightseeing “Car Rouges”, or red coaches, in the French capital.

The company said in a statement that its passengers were questioned as witnesses and that it is working “closely” with the police investigators.

The company said it was conducting its own internal investigation.

Traffic was off-limits in large areas of the city’s centre until midnight due to the sports events.