A Man Attacked a March for Israeli Hostages in Colorado. Here’s What to Know.

The authorities said they were investigating an attack in Boulder, Colo., on Sunday as an act of terrorism, after a man used a “makeshift flamethrower” to attack demonstrators marching peacefully in support of Israeli hostages in Gaza.

Eight people were hospitalized with burns and other injuries, and two of them were in serious condition, officials said. The suspect was arrested.

The attack may intensify deep unease in the Jewish community in the United States. In recent months, two Israeli embassy aides were murdered in Washington, and a man set fire to the residence of Gov. Josh Shapiro of Pennsylvania, who is Jewish.