Micah Johnson was killed after five police officers were shot dead at a Black Lives Matter rally in Texas
Along with the weapons, police also found a journal of combat tactics. Detectives are now in the process of analyzing the information contained in the journal.
Before he died, Micah Xavier Johnson said he was acting alone and was not affiliated with any terror group.
The 25-year-old told a police negotiator he was upset at white people and wanted to kill them, especially white officers.
Negotiations between officers and Johnson eventually broke down, and after an exchange of gunfire he was killed by a robot-delivered bomb.
Five officers died and nine other people were injured in the shootings.
According to a police report, Johnson had no criminal history. Information provided through the course of the investigation indicated that the suspect was an Army veteran, with some describing him as a 'loner'.
Dallas police chief David Brown described the shootings as a "well-thought-out evil tragedy".
Dallas Mayor Mike Rawlings said police believe that Johnson was the lone shooter, adding that he had "written manifestos on how to shoot, move, shoot, move. And he did that."
"We believe now that the city is safe and that the suspect is dead and we can move onto healing."
He described the past day as "a veritable tale of two cities - the heroism of police officers but, at the same time, it has been a tale of cowardice of an assassin".
He also acknowledged that this incident was the symptom of a much bigger problem in the United States.
"We will not shy away from the very real fact, that we as a city, as a State, and as a Nation are struggling with racial issues.
"This is on my generation of leaders. It is on our watch that we have allowed this to continue and to fester.
"We have led the next generation down a vicious path of rhetoric and actions that pit one against the other."
The shootings took place at a protest against the recent fatal shootings of two black men by police.
Police say officers have also been targeted in Tennessee, Georgia and Missouri, with the attack in Tennessee occurring hours before the one in Dallas.
The Tennessee Bureau of Investigation says that the attacker told authorities he was frustrated by the killings of black men in Louisiana and Minnesota.
Additional reporting by IRN