TOKYO – In a ghastly spectacle of a sort rarely seen in this orderly city, a man set himself on fire in front of horrified crowds at Tokyo's busiest train station Sunday in what appeared to be a lone protest against efforts to weaken Japan's antiwar Constitution.

The police provided few details about the man, who survived with burns all over his body after being rushed to a Tokyo hospital. Firefighters appeared either to have been warned or to have discerned the man's intentions, because they were on hand to douse him quickly with water once he set himself on fire with a liquid that looked like gasoline.

The self-immolation took place in broad daylight in front of hundreds of onlookers, who used cellphones and other devices to post graphic videos and photos on social media sites.

The images show a middle-aged man who sat cross-legged atop the scaffolding of a pedestrian bridge in front of the busy Shinjuku train station. At first, he used a megaphone to speak to gathering crowds.

While most of the images are silent, several postings said the man told the crowd that he opposed efforts by Prime Minister Shinzo Abe to loosen restrictions in the Constitution on the use of military force, which is interpreted as allowing Japan to act only in self-defense.

Abe has called for a new interpretation that would allow the armed forces also to contribute to the defense of allied nations under attack, something they cannot now legally do. While Abe says Japan needs more robust military alliances to offset the growing might of China, opponents on the left have staged small street protests to warn that the change could embroil Japan in distant, U.S.-led wars.