A Las Vegas police officer, his wife and son are dead after an apparent double murder, suicide and arson at their home, authorities said.
Officials did not immediately identify the police officer or the family members, but the home is known to be owned by Hans Walters, a lieutenant with 20 years service in the Metropolitan department.
"There was an incident today (Monday) involving one of Metro's lieutenants," Clark County Sheriff Douglas Gillespie said.
"Several bodies were discovered."
The sheriff said the investigation in Boulder City, about 20 miles southeast of Las Vegas, was being handled by police in neighbouring Henderson.
Police there said a man called 911 at about 8.20 am on Monday and told a dispatcher that he had killed his wife and child, set his house on fire and would shoot anyone who approached.
Officers arrived to find the homeowner with a handgun in the doorway of the burning house, before he retreated inside and apparently killed himself.
No shots were fired by police or SWAT officers.
The bodies of a 52-year-old man, a 46-year-old woman and a boy were found inside later.
Hans Walters was married to another former Las Vegas police officer, Kathryn Walters.
Officials said the boy was believed to be about seven.