A white man was sentenced on Thursday to 10 years in prison after pleading guilty to shooting three young black men who were trying to evacuate in the aftermath of Hurricane Katrina, the authorities said.

Shortly after the hurricane ravaged New Orleans in 2005, the man, Roland J. Bourgeois Jr., 55, fired a shotgun at the three men because they were black and entered the neighborhood in which he lived, the United States Attorney’s Office for the Eastern District of Louisiana said in a news release.

The men, who were all injured in the shooting, had been trying to reach a ferry landing that state and federal agencies were using as an evacuation site.

According to court documents filed alongside the defendant’s plea agreement in October, Mr. Bourgeois and other white men who lived nearby decided to forcibly prevent people they called “outsiders” — including black residents — from entering the neighborhood of Algiers Point, which borders the Mississippi River. The white men used fallen trees to barricade the streets near their homes and patrolled the streets with guns, the documents said.