Image copyright Facebook Image caption Facebook images show Micah Johnson giving a black power salute and dressed in military uniform
Bomb-making material, rifles, ammunition and combat journal have been found at the home of the main suspect in the Dallas shooting.
Police said the material was found when they searched the home of Micah Johnson in the Dallas suburb of Mesquite.
Five police officers were killed and seven wounded in a hail of gunfire during a protest against the shooting of black men by police.
Johnson died following a long stand-off with police in central Dallas.
Police confirmed media reports that the 25-year-old army veteran was the person killed when they remotely detonated explosives they sent into the car park where he was holed up.
They said he had no criminal history.
The protest in Dallas took place after this week's deaths of Philando Castile in Minnesota and Alton Sterling in Louisiana.
Police Chief David Brown said the suspect had told a negotiator that he had wanted to kill white people, especially white police officers, because he was angry about the recent shootings of black men by police.
Mr Brown added that the man had said he was not affiliated with any groups and he had acted alone.
Media caption Sidney Johnson captured the chaos in the aftermath of the shootings
US Homeland Security Secretary Jeh Johnson appeared to confirm this in a statement later on Friday.
"At this time there appears to have been one gunman with no known links to or inspiration from any international terrorist organisation," he told a news conference in New York.
Police arrested three people and initially said they believed at least two snipers had caught police in crossfire, shooting some officers in the back.
On Thursday, five police officers were killed and seven were injured after a sniper attacked a public protest march in downtown Dallas, Texas. Sources indicate at least three other people were taken into custody for questioning relating to the attack. The march was held to protest the shooting deaths of Alton Sterling in Louisiana and Philando Castile in Minnesota during engagements with police officers.

Police identified 25-year-old Micah Johnson as the suspect. Johnson had previously served in the US army, and police reported he said he wanted to exact revenge upon police officers after news of Sterling and Castile's deaths. Ammunition and weapons were found inside Johnson's home. Dallas Police reported the policemen were shot at from a height. Officials said two civilians were also injured in the attack. 
File photo of police car lights.
Micah Johnson served for the  from 2009 until early 2015, including a tour of Afghanistan. Johnson had no criminal record.  His attack was reported to be a lone mission.

After the attack earlier on Thursday, police killed Micah Johnson in 's parking lot by a bomb explosion.

Hillary Clinton, 2016 United States presidential election candidate and favorite for the Democratic nomination this July, said, "There is too much violence, too much hate, too much senseless killing, too many people dead who shouldn't be. No-one has all the answers. We have to find them together." 

After Johnson was killed, , Dallas' mayor, said "We believe now the city is safe".