The Saudi gunman who attacked a Florida navy base on Friday played videos of mass shootings at a dinner beforehand, US media reports say.
Mohammed Alshamrani – who was training at the Pensacola base – killed three sailors before being shot dead.
The US Navy said the sailors “showed exceptional heroism and bravery in the face of evil”.
They were named as Joshua Kaleb Watson, 23, Mohammed Sameh Haitham, 19, and Cameron Scott Walters, 21.
Several Saudi trainees have reportedly been held for questioning.
Authorities have not alleged that they were involved in the attack, which took place across two floors in a classroom on Friday morning.
The gunman played the mass-shooting videos to others at a dinner earlier in the week, several US media outlets report, quoting an anonymous official briefed on the investigation.
A Twitter user appearing to match Alshamrani’s identity had also made a series of anti-US posts before the shooting, an online monitoring group says.