DALLAS (CBSNewYork/AP) -- There was a growing memorial outside of the police headquarters in Dallas on Monday night, as the city paused to honor the police officers killed in last week's ambush.
Flowers and notes of condolences were left on a police car remembering the five officers who were shot and killed during a Black Lives Matter protest, and thousands of people gathered at city hall for a vigil.
A memorial service was to be held Tuesday, with President Barack Obama, Vice President Joe Biden, and former President George W. Bush expected to attend.
While he is in Dallas on Tuesday, President Obama will also speak privately with the families of the slain officers.
The fallen officers' heartbroken families were remembering their final moments with their loved ones.
A 9-year-old daughter remembered saying goodbye to her father as he left for work that day.
"He said to me, 'What if this is the last time you ever kiss or hug me?" Caroline Smith said as she broke down crying. "That's probably the first time he ever said that. It just felt different to me. I thought something bad was going to happen."
Her father Sgt. Michael Smith was a 28-year veteran of the Dallas Police Department. The 55-year-old was just two years away from retirement.
Five Port Authority Police Officers left on Monday for the 1,500 mile drive to Dallas. They are taking a 'relief canteen trailer' to provide refreshments to the thousands of officers expected to attend the funerals.
"We need to go down there. Everyone supported us throughout the country on 9/11. We're going down to Texas to console our brother officers, feed our brother officers, do whatever we can to help our brother officers," Port Authority PBA President Paul Nunziato said.
The Port Authority officers will also represent the department at the funerals which begin Wednesday, and are expected to wrap up on Sunday. The Port Authority Police understand tragedy, they lost 37 officers on 9/11.
As CBS2's Tony Aiello reported, a vigil was held in Brooklyn on Monday night, with people of goodwill gathering to pray for peace during a trying time.
They lit candles at the Grand Army Plaza, but also cursed the darkness of last week.
"We are all victims - whether police are victimizing citizens or citizens are victimizing police," said the Rev. A.R. Bernard of the Christian Cultural Center said.
Christy Burnham brought her sons to join faith leaders from many traditions praying for peace and reconciliation.
"The main thing is just for the violence to stop all over -- police brutality, black against black crime, gun violence," she said.
One irony with Monday's vigil -- it was interrupted by sirens as NYPD units from across Brooklyn rushed to the police involved shooting in the 62nd Precinct.
As CBS2's Dick Brennan reported, the doctors who treated the officers spoke out for the first time on Monday.
"I abhor what has been done to those officers," Dr. Brian Williams said.
An emotional Dr. Williams of Parkland Memorial Hospital treated the officers who were shot in the attack.
"I understand the frustration, and the anger, and the distrust of law enforcement," he said, "But they are not the problem. The problem is the lack of open discussion of the impact of race relations in this country and I think about it every day that I was unable to save those cops when they came in here that night."
Williams said it's time to bring people together.
"The killing, it has to stop. Black men dying and being forgotten, people retaliating against the people who are sworn to defend us, we come together to end all of this," he said.
The Dallas police chief defended the department's use of a robot-delivered bomb to kill the suspect in Thursday's shooting.
Chief David Brown said at a news conference Monday that the suspect, 25-year-old Micah Johnson, had "already killed us in a grave way, and officers were in surgery that didn't make it.''
"This wasn't an ethical dilemma for me,'' he added.
Johnson shot and killed five officers and wounded nine more officers and two civilians during a protest Thursday in downtown Dallas. He was killed by a bomb delivered by a remote-controlled robot after negotiations with authorities failed.
"We asked him, 'Do you want to come out safely or do you want to stay there? We're going to take you down,' and he chose the latter," said Mayor Mike Rawlings.
Brown described the robot Monday, which he said was purchased in 2008 for $151,000 and is still functional.
Some experts have raised concerns about this new method of neutralizing a threat. They've called for a full review of the decision to deliver lethal force using a robot. Others said they don't expect police to use robots like this except in extreme cases.
Brown also clarified Monday where Johnson was killed, saying it happened on the second floor of a community college and not a parking garage as authorities previously described.
He said the department has misspoke for days and that Johnson died inside El Centro Community College. Brown did not provide more details, including the location of negotiations that came before the bomb.
The chief also said that authorities are downloading more than 170 hours of officers' body camera footage and collecting "countless hours'' of dashcam video.
He said 11 officers fired weapons at Johnson and that two used the explosive device.
Police said Johnson had been planning an even bigger attack. Inside his home, investigators found a journal containing combat tactics and an arsenal two years in the making, including guns and bomb making materials.
"This suspect had been practicing explosive detonations and the materials were such that they were large enough to have devastating effects throughout our city," Brown said.
CBS News has learned that Johnson had hundreds of rounds of ammunition attached to his body, indicating that he was ready to kill more people.
Investigators believe that he planned for a larger attack, but saw an opportunity to ambush officers at the protest.
Police also said Johnson used his own blood to write the letters "RB" on a wall before he was killed. They are still trying to find out what the letters stand for.
In the meantime, Brown encouraged those who have problems with law enforcement to become part of the solution.
"Get off that protest line and put your application in. We will put you in your neighborhood and you can help resolve some of the problems that you are protesting about," he said.
Meanwhile, Johnson's parents said they are surprised by his violent rampage and noted he returned from an Army deployment to Afghanistan a changed man.
Johnson's father, James Johnson, said in an interview posted on TheBlaze website Monday that he "didn't see it coming.'' Through tears, Johnson said, "I hate what he did.''
His mother, Delphine Johnson, said that as a child her son wanted to join the police, but that after serving six years in the Army Reserves, he became a "hermit.''
The family said he never showed signs of hatred for certain groups of people, but that he hated "injustice.''
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