A security cordon was set up and the public were told to avoid central Toulouse as a police operation was launched on Friday morning.
According to local newspaper La Dépêche, a man entered the cathedral during the 8am mass, put a parcel in front of the altar and then left, shouting incomprehensible words.
A priest at the Cathédrale Saint-Etienne tried to stop him as he fled. He was shoved, but not injured.
A security cordon was set up and the area around the cathedral evacuated as police dealt with the package and the incident was declared over at about 10am.
Interior Minister Gérald Darmanin gave a press conference later on Friday, at which he said: “This morning at around 8:30am, the congregation of the Cathedral of Saint-Etienne in Toulouse reported that an individual had placed a package in front of the altar of the Cathedral during Mass.
“According to the information we have at this stage, no claims have been made. In his escape, this individual pushed the sacristan who was not injured. The individual is being actively sought.
“The cathedral was evacuated and a security perimeter around it was immediately set up by the police, and bomb disposal teams used.
“A parcel resembling an improvised explosive device, without any ignition device, was discovered and neutralised by law enforcement.”
— Gérald DARMANIN (@GDarmanin) April 8, 2022
Early on Friday afternoon, it was announced that the man had been arrested.