HOUSTON — A gunman opened fire during a cookout for a Cowboys game at a suburban Dallas home on Sunday night, killing eight people before a police officer fatally shot him, the authorities said.

An officer with the Plano Police Department responded to the home within minutes of 911 calls and found several people wounded in the backyard of the home, located in the 1700 block of West Spring Creek Parkway, a residential area surrounded by parks near Spring Creek. After the officer heard additional gunshots, he entered the rear of the home and shot the man, Chief Gregory Rushin of the Plano Police Department said at a news conference on Monday afternoon.

Eight people, including the gunman, died at the home. Two people were taken to a hospital, and one later died. Chief Rushin said he did not know the survivor’s condition.

The Police Department released few details on Monday about the episode, the worst mass shooting in Plano’s history. The city, a fast-growing suburb of 260,000 north of Dallas, had fewer than eight homicides each year during the past decade.