Instead, Micah X. Johnson improvised and used his military training to gun down officers during a demonstration on Thursday evening, Dallas Police Chief David Brown told CNN. It was the deadliest day for U.S. law enforcement since the Sept. 11, 2001, attacks.
"We're convinced that this suspect had other plans," said Brown, adding that the recent deaths of two black men at the hands of police in Minnesota and Louisiana led the Texas shooter to "fast-track" his plans and launch his attack.
Johnson, 25, a black veteran who served in Afghanistan, took advantage of a spontaneous march that began toward the end of the protest over those killings. Moving ahead of the demonstrators in a black Tahoe SUV, he stopped when he saw a chance to use "high ground" to target police, Brown said.
He said a search of Johnson's home turned up signs the gunman had practiced using explosives, and that other evidence suggested he wanted to use them against law enforcement targets.
Before being killed by a bomb-equipped robot, Johnson sang, laughed at and taunted officers, according to Brown, telling them he wanted to "kill white people" in retribution for police killings of black people. "He seemed very much in control and very determined to hurt other officers," the police chief said.
Speaking at a local hospital, 12-year-old Jamar Taylor told reporters how he was separated from his mother and lost his telephone when the bullets began to fly.
"I was scared. I really didn't know what was going to happen," a sobbing Jamar said. His mother, Shetamia Taylor, was shot in the leg. A stranger helped the boy to safety.
Brown said police had been caught off guard when some protesters broke away from Thursday's demonstration, and his officers were exposed to the gunfire as they raced to block off intersections ahead of the marchers.
Johnson's military training helped him to shoot and move rapidly, "triangulating" his fire with multiple rounds so that police at first feared they were facing several shooters.
Brown vigorously defended the decision to use a robot to kill the gunman, saying "about a pound of C4" explosive was attached to it. And he said Johnson scrawled the letters "RB" in his own blood on a wall before dying.
"We're trying to figure out through looking at things in his home what those initials mean," the police chief said.
At the Cathedral Shrine of the Virgin of Guadalupe in downtown Dallas, Roman Catholic parishioners gathered on Sunday for their weekly service and to remember the fallen officers.
Reverend Eugene Azorji based his sermon on the Biblical tale of the Good Samaritan, which chronicles the life-saving actions of a stranger to a man in need.
"I would like you to join me and asking, 'Who is my neighbor?'" Azorji, who is black, told the congregation. "Those who put their lives on the line every day to bring a security and peace, they represent our neighbor."
A candlelight vigil is due to be held at 8 p.m. on Monday in Dallas City Hall plaza.
PROTESTS AND ARRESTS
The mass shooting amplified a turbulent week in the United States, as the issues of race, gun violence and use of lethal force by police again convulsed the country.
Even as officials and activists condemned the shootings and mourned the murdered officers, hundreds of people were arrested on Saturday as new protests against the use of deadly force by police flared in several U.S. cities.
Particularly hard hit was St. Paul, Minnesota, where 21 officers were injured as police were pelted with rocks, bottles and fireworks, officials said.
Three countries have warned their citizens to stay on guard when visiting U.S. cities rocked by the protests.
"Young males are asked to exercise extreme caution in affected cities in their interactions with the police. Do not be confrontational and cooperate," the Bahamas government said. Bahrain and the United Arab Emirates also issued advisories.
Speaking in Madrid during a European tour, U.S. President Barack Obama said attacks on police over racial bias would hurt Black Lives Matter, a civil rights movement that emerged from the recent police killings of African-Americans but has been criticized for vitriolic social media postings against police, some of them sympathetic to Johnson.
"Whenever those of us who are concerned about failures of the criminal justice system attack police, you are doing a disservice to the cause," the United States' first black president told a news conference.
Some people would always make "stupid" or "overgeneralizing" comments, Obama added, but well-meaning activists could not be held responsible for everything said at a protest.