A Minneapolis man on Sunday shot and killed his ex-wife and their two sons and then himself.

Kjersten Schladetzky was killed in her home, while her 11-year-old and 8-year-old sons were killed in the front yard. The shooter, whose name has not been released to the public, was found dead in the house.

The two boys were found alive when police arrived on the scene, having fled outside before being shot. They eventually succumbed to their injuries and were pronounced dead after being brought to one of the officers’ squad cars.

“I actually thought it was a game at first, like the dad was kind of fake shooting them,” said Erik Wiltscheck, a neighbor who witnessed the shooting and was one of the first to call 911. “But then all of sudden a loud ‘boom, boom, boom,’ and the kids are trying to get up.”

Officers first responded to calls about the shooting at 10 a.m., leading to an hours-long standoff between the shooter and teams of police and SWAT members. A perimeter was established after more shots were heard coming from the home and residents from the neighboring homes were evacuated. After several hours of attempting to make contact with the shooter, police entered the home and found the man and his ex-wife dead.

While a motive for the shooting has yet to be officially determined, authorities believe it to be a domestic incident. According to the Minneapolis Star Tribune, the house was in Schladetzky’s name and the couple had finalized their divorce in the summer.

“I just started tearing up and crying,” Wiltscheck said. “It’s kids. They’re so full of life, and to see lifeless bodies was just really, you just can’t imagine how horrible that really is.”

crime scene
This is a representational image of a crime-scene tape in Chicago, Illinois, in March 2005. Getty Images/Scott Olson