A man set himself on fire on Friday afternoon near the Lower Manhattan courthouse where jurors were being chosen for the criminal trial of former President Donald J. Trump.

The man, who had lingered outside the Manhattan Criminal Courthouse earlier this week, doused himself with accelerant at around 1:35 p.m. in Collect Pond Park, across the street from the building. Onlookers screamed and started to run, and soon, bright orange flames engulfed the man. He threw leaflets espousing anti-government conspiracy theories into the air before setting himself on fire.

People rushed and tried to put out the flames, but the intensity of the heat could be felt from some distance.

After a minute or two, dozens of police officers arrived, running around and climbing over barricades to extinguish the blaze. The man was loaded into an ambulance and rushed to a hospital burn unit. He died on Friday night.

City officials identified the man as Max Azzarello, 37, of St. Augustine, Fla. Mr. Azzarello had appeared outside the courthouse on Thursday, holding a sign displaying the address of a website where the same pamphlets were uploaded. The top post of the website says, “I have set myself on fire outside the Trump Trial.”