Well, it's clearly a clickbait title. It's called "The straw that broke the camel's back".

Uiryeong massacre
On the afternoon of April 26, 1982, Woo had an argument with his live-in girlfriend, Chun Mal-soon (전말순; 全末順), after she had woken him by swatting a fly on his chest.Enraged, he left the house and sat in the police armory and began consuming large amounts of whiskey. He became moderately drunk and raided the police armory of its weapons and built a personal arsenal. He stole a single high-powered rifle and some grenades and walked out of the armory with these in hand. By that time, it was around dinner hour. He walked from house to house, and abused his position as a police officer to make people feel safe. Then he shot the victims, or simply blew the entire family up with a grenade. He continued this pattern for the next eight hours, and into the early morning hours of April 27.

Village to village
When Bum-Kon had shot a certain number of people in a village, he ran to another village and started killing. Eventually, he had torn through five villages in the Uireyong province. The victims could not defend themselves, as they thought that he was a friendly officer simply handling disturbances. And if they were attacked, they could not fight back, as guns are banned to civilians in Korea.

Suicide
In the early hours of April 27, Bum-Kon took his final two grenades and strapped them to this body. He grabbed three people as he set the fuse of the grenades. They became his final victims, as he blew himself up, killing the three he had taken hostage. The world's worst spree killing was finally over.
(From Murderpedia)