Paul Barril was reportedly in a state of delirium, possibly linked with medication he is taking to treat Parkinson’s disease.
He had isolated himself for several hours before surrendering to police.
Former colleagues said Barril had never posed such a threat, but it’s not the first time he’s made headlines.
Paul Barril had a long career in France's national military police, in which he helped set up and run an elite unit specialising in freeing hostages and other crisis situations.
He went on to create the French presidential office’s counterterrorism unit under president Francois Mitterrand in the 1980s.
During that time, he became the subject of controversy - accused of but never charged for allegedly planting weapons in the homes of Irish nationalists.
He also received a six-month suspended sentence in 2005 for his role in a phone tapping scandal at a French newspaper.
Later in his career, Barril ran a private security business for a number of African leaders.
He’s faced accusations of being involved in the 1994 plane crash of Rwandan president Juvenal Habyarimana, the event that triggered the country’s genocide.
He’s been interrogated several times in a French investigation into the crash, and earlier this year, a French NGO called for him to be indicted for complicity.
Following Monday's events, Barril is expected to spend some time in hospital.