(CNN) -- A right-wing historian and author killed himself inside the Notre Dame Cathedral in Paris Tuesday in front of horrified tourists, police said.
About 1,500 people at the cathedral were evacuated, CNN affiliate BFM reported. The site is one of the world's most prominent churches and a huge tourist attraction in the French capital.
BFM identified the man as Dominique Venner, 78.
Le Monde newspaper quoted a rector at the cathedral, who said the man placed a letter on the altar and then shot himself
On his blog, Venner has lashed out against same-sex marriage and what he called a future Islamist takeover of France.
In a post published Tuesday, he wrote, "The essence of a man is in his existence and not in another world. It's here and now that you have to play out your destiny until the last second. And this last second has as much importance as the rest of the life."
In the blog, Venner voiced his support for those expected to take part in a massive demonstration in Paris May 26 against same-sex marriage. But he said their fight should not be limited to that issue, and they must also denounce what he predicted would be the replacement of the French and European population with Muslims.
"There certainly have to be new actions, spectacular and symbolic, to shake up the sleepiness, to shake the numbed consciences and wake up the memory of our origins," the blog said. "We're entering into a time when words must be authenticated by actions."
Right-wing politician Marine Le Pen tweeted about her "respect" for him. His "last gesture, which was highly political, was to try to wake up the people of France," she wrote.
Some took to Twitter to slam Le Pen for the remark.
CNN's Alanne Orjoux and Josh Levs contributed to this report.