Hundreds of commuters and holidaymakers were evacuated from one of Paris' busiest metro lines on Tuesday evening after a power failure halted the driverless trains.
The failure happened at around 20:10 (1810 GMT) between two stations on Line 1 in the French capital's upmarket Marais district, a spokesman for the operator RATP said.
Traffic didn't fully resume until 23:30.
Passengers needed to be evacuated from at least eight trains, with many walking to the nearest station in the dark along the tracks. Reports say passengers in the first of the blocked trains forced the doors open themselves and walked along the tracks to the nearest station.
The fire service said five people were treated for heat exhaustion after being stuck underground as France is experiencing a weeks-long heatwave.
Passengers took to Twitter to tell of their chaotic ordeal and to call on Paris transport operator RATP to help. But passengers complained they were left in the dark and had to fend for themselves in sweltering temperatures.
"Parents, with their children in tears forced to leave the Metro along the tracks without any help from RATP. It lasted over one hour and a half and no exaggeration it was 60C in the tunnel," said one passenger.
There were reports of a pregnant woman fainting and video images shown a mother and her one-month old baby being evacuated. Other video images showed passengers drenched in sweat.
The incident on Line 1 -- which serves some of Paris' most popular landmarks including the Louvre, the Tuileries garden and the Champs-Elysees --
comes after tens of thousands of people were stranded at a train station in the capital following an electrical fire over the weekend.
