A man has been arrested in connection with a fire at Nantes cathedral that caused significant damage to the 15th-Century structure.
The blaze destroyed the grand organ and blew out stained glass windows.
A 39-year-old man who is being questioned worked at the cathedral as a volunteer and was in charge of locking up on Friday night, TV channel LCI said.
Prosecutor Pierre Sennes said the man had been taken into custody so that alleged inconsistencies in his schedule could be examined.
Mr Sennes said that three fires had been started with no sign of a break-in and that an investigation for possible arson is underway.
It took several hours to bring the blaze under control after it began yesterday morning.
Flames were completely extinguished by the afternoon.
Reporting by IRN