New York, New York - A man has died after setting himself on fire in a park opposite the New York courthouse hosting Donald Trump's criminal hush money trial, according to reports.

The man died of his injuries in hospital, NBC News and other outlets said, citing police sources.

The man, identified as Maxwell Azzarello of St. Augustine, Florida, spread pamphlets containing conspiracy theories around the park, witnesses said.

He poured a liquid over himself and set himself alight, as bystanders screamed and tried to help. After a short time, police officers arrived and extinguished the flames.

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Azzarello was initially taken to hospital by ambulance, where he was pronounced dead. His motive remains unclear, but police don't think a specific person or group was being targeted.

The incident took place in Collect Pond Park, directly opposite the courthouse where the Trump's criminal trial, which had just seated its jury, is currently taking place.

The courthouse is extensively cordoned off and numerous police officers are on permanent duty there. Dozens of media representatives with cameras and broadcast vans are gathered around it.

Opponents and supporters of Trump are allowed to gather for demonstrations in the park, but so far only a few have done so on the days of the trial. The grounds are surrounded by barricades, but there are also open entrances.

NBC cited New York City Fire Commissioner Laura Kavanagh, who said four cops and one court officer were lightly injured in the incident.