The blast happened around 1 p.m. and was heard from blocks away. Police said a man set off a device made from fireworks that injured his hand. The man, 26, was detained and sent to a hospital. His injuries were not life threatening and no one else was hurt, police said.

“Other than the bomber, no other people were injured and there was no damage to embassy property,” the embassy said in a security notice.

A visa agent who said he was about 30 feet away when the blast occurred said the source appeared to be an explosive device, set off by a man who had been trying to call attention to a human rights issue.

Earlier in the day, a woman who had also been protesting was arrested after dousing herself in gasoline, the agent said. It was not clear whether the two incidents were related.

Images shared on social media showed a large number of people looking toward the site of the explosion and gray smoke drifting over the street.

The street in front of the embassy, Tianze Road, which is also near the embassies of India and Israel, was closed for about an hour after the blast. Soon after the street reopened, a new line began to form outside the embassy compound.

The U.S. Embassy, in northeastern Beijing, is a well-protected compound. The facility opened in 2008 with a dedication ceremony attended by then-President George W. Bush. Security inside the visa area is strict, with no electronic devices or large bags allowed inside.

China has a long-standing system that allows people to petition the government over grievances. But many petitioners say they never receive justice, and are deterred by security officials and hired thugs who assault and detain them. Some, after years of fruitless petitioning, turn to violence.

In 2013 a man who had been paralyzed from the waist down from a beating by security officials set off an explosive device in Beijing Capital International Airport, injuring only himself. Documents that circulated online revealed his long struggle to receive compensation. “Almost without hope, petition road endless,” he wrote.

A man who was reportedly angered by the lack of adequate redress for the demolition of his home set off three explosions outside government buildings in Jiangxi province in 2011, killing himself and two others.

This article originally appeared in The New York Times.

Chris Buckley and Austin Ramzy © 2018 The New York Times