Emergency responders on Sunday had rushed to the scene just before 1:00 pm (1800 GMT) in response to a "call for the person on fire outside the Israeli Embassy," according to a message on X, formerly Twitter, by the capital city's fire department.

They arrived to find that officers from the Secret Service -- the US law enforcement agency tasked with protecting embassies in Washington -- had already extinguished the fire.

The man, who was identified by media and social media platforms as Aaron Bushnell, 25, had filmed himself shouting "Free Palestine" as he lit himself on fire, according to footage shared on social media.

He was initially transported to hospital with "critical life-threatening injuries," the fire department said.

An Air Force spokeswoman told AFP Monday morning that the unnamed "individual involved in yesterday's incident succumbed to his injuries and passed away last night."

"We will provide additional details 24 hours after next-of-kin notifications are complete."

A spokesperson for the Israeli embassy said no staff were injured in the incident, and that the man was "unknown" to them.

In the video shared on social media, the man is seen wearing military fatigues and declaring he will "not be complicit in genocide" before dousing himself in liquid.

He then lights himself on fire while yelling "Free Palestine!" until he falls to the ground.

The video was reportedly first shared in a live stream on the social platform Twitch.

With the death toll in Gaza nearing 30,000 and the wounded climbing over 70,000, international and domestic pressure has been increasing on the US to rein in its ally Israel and call for a ceasefire.

The US has backed the Israeli genocidal campaign against the Palestinians in Gaza with vetoes against a ceasefire in the UNSC and round-the-clock shipments of arms and munitions and billions of dollars in additional financing to Tel Aviv.

Since 7 October, hundreds of thousands of people in the US have been protesting against Washington's support of Israel in its war on Gaza and pressuring the Biden administration to endorse an immediate ceasefire.