Police have identified the shooter as Micah Xavier Johnson, a 25-year-old Army veteran who lived in Mesquite.
Johnson open fired during a peaceful protest against police brutality in the wake of the deaths of two unarmed black men at the hands of officers earlier in the week.
The Associated Press reported that the Dallas police found bomb-making materials, ballistics vests, rifles, ammunition and a journal full of combat tactics during a search of his residence.
The incident has worsened the tense race relations in the country, and is being dubbed the deadliest attack on law enforcement authorities in the U.S. since the September 11 violence.
FBI investigators look over the crime scene in Dallas, Texas, U.S. July 8, 2016 following a Thursday night shooting incident that killed five police officers.
President Barack Obama, Illinois Gov. Bruce Rauner and Iowa Gov. Terry Branstad ordered all flags to be flown at half-staff until sunset on Tuesday to honor the officers who were killed.
Earlier, Dallas police said the main shooting suspect had told negotiators he was not affiliated with any groups.
Johnson was a private first class from the Dallas suburb of Mesquite with a specialty in carpentry and masonry. May God bless all who were affected by last night's event. King says anyone blaming Black Lives Matter "is sick".
Officer U-Londa Peterson finished her shift with the Dallas Area Rapid Transit on Thursday afternoon, then went home to her family visiting from California.
He said he wanted to exterminate whites, "especially white officers", officials said.
He joined the DART police department in 2009, authorities said.
South Elgin police Chief Chris Merritt exhorted his officers Friday to continue doing their jobs with professionalism.
Peterson has been with DART for 18 years, and on Friday, she stopped by a growing memorial outside the Dallas Police Department with her family and other law enforcement officers.
"Honestly, for the first time in my entire married life with this man, I was actually afraid today", she said.
In suburban St. Louis, a motorist shot an officer at least once as the officer walked back to his auto during a traffic stop, police said.
Speaking to The Telegraph, Johnson's friend said "He was upset".
"Police officers are guardians of this great democracy - the freedom to protest, the freedom of speech, the freedom for expression".