It’s [day] in America, so we’re once again grappling with the tragedy of a mass shooting, and once again it’s a school shooting. And once again, as we see images of terrified parents waiting to find out if their children have survived, paired this time with cell phone videos taken inside the school by equally terrified teenagers, politicians who have the power to do something about mass shootings are instead offering only thoughts and prayers. Nikolas Cruz, 19, has been charged with 17 counts of premeditated murder in the Parkland, Florida, school shooting.

By the end of the rampage, Mr. Cruz had killed 12 people inside the school and three outside it, including someone standing on a street corner, Broward County Sheriff Scott Israel said. Two more victims died of their injuries in local hospitals. The aftermath at the school was an eerie shrine, with chairs upended, a computer screen shattered with bullet holes and floors stained with blood.

Cruz had previously been expelled from Marjory Stoneman Douglas High School, and there’s some reason to believe that he may have something in common with many other mass shooters: an abusive relationship with women.

Mr. Gard said that after the shooting, he learned from several students that Mr. Cruz was obsessed with a girl at the school to the point of “stalking her,” a point the authorities did not raise in news briefings near the scene.

But the thing he had in common with all American mass shooters is American gun laws and American gun culture. And he took part in a gruesome trend:

With the Parkland shooting, three of the 10 deadliest mass shootings in modern United States history have come in the last five months.