Authorities are investigating a Massachusetts shooting that left two Black people dead as a hate crime. On Sunday (June 27), investigators said they discovered “some troubling white supremacist rhetoric” written by the white gunman, 28-year-old Nathan Allen.

According to police, Allen stole a plumber’s truck in Winthrop, Massachusetts on Saturday (June 26) and crashed it into a house. He then fatally shot two Black bystanders before being killed by police at the scene.

The bystanders were identified as 58-year-old David Green, who was a retired state police officer; and 60-year-old Ramona Cooper, a staff sergeant in the Air Force. Winthrop Police Chief Terence Delehanty said Green was struck by four bullets in the head and three in the torso, and Cooper was shot three times in the back.

Before crashing into the house, Allen allegedly collided with another vehicle that had two passengers. Both people were taken to a hospital to be treated for their injuries but are expected to survive.

A hate crime probe into the shooting was opened after investigators found notes written by Allen that contain “antisemitic and racist statements against Black individuals.” Suffolk County District Attorney Rachael Rollins said the gunman also wrote about white people being “apex predators” and had drawings of Nazi swastikas.

“He walked by several people that were not Black and they are alive. They were not harmed,” Rollins said Sunday. “They are alive and these two visible people of color are not.”

“This is a sad day. These two people protected our rights. They fought for us to be safe and to have the opinions that we have and they were executed yesterday,” Rollins said of Green and Cooper. “And we will find out why and find out more about this man who did this.”

She added, “There is a growing national and global problem with extremism and white supremacy. The FBI believes the most serious domestic violent extremist threat comes from ‘racially or ethnically motivated violent extremists, specifically those who advocated for the superiority of the white race.’”