The man suspected of shooting dead 10 people at a supermarket in Buffalo, New York, deliberately sought a site with a high black population, authorities say.
The suspect, Payton Gendron, 18, drove more than 320km to carry out the attack, police say.
The attack is being investigated as an act of racially motivated violent extremism.
Buffalo Mayor Byron Brown said the suspect arrived intending to take as many black lives as possible.
A 180-page document seemingly authored by Mr Gendron has emerged, in which he describes himself as a fascist and a white supremacist.
Police believe that the gunman planned to continue his rampage, following the attack had he not been stopped, Mr Gramaglia told CNN, with evidence suggesting that he had plans to target a second store. End.
