Attack on police in Dallas

A group of motorcycles, organized by the group Ride DFW, ride past the memorial in front of police headquarters to pay respects in Dallas on July 10, 2016.

Mourners visit the Police Headquarters memorial for officers killed in the recent sniper attack in Dallas on July 10, 2016.

Officers are deployed around Dallas police headquarters because of an unspecified threat.

Dallas police officers check out an unspecified threat around the headquarters.

Seven-year-old Jacob Flanagan greets Assistant Police Chief, Gary Tittle, with his Mom, Jennifer Cobb, in front of the Dallas Police Headquarters.

Djuana Franklin weeps for the slain police officers at a memorial at the Dallas police headquarters.

Flowers, handwritten notes, balloons, candles and other mementos are left on squad cars parked at the Dallas Police Department in a memorial to the slain officers.

Rachel Simon embraces her daughter Abigail Simon, 13, as they pay their respects to the slain officers at a memorial outside Dallas Police Department.

A large American flag flies at half mast framed by the Dallas skyline in the aftermath of the deadly police shooting.

Flowers, cards, balloons, candles and other mementos form a makeshift memorial at the Dallas Police Department.

Investigators comb through the crime scene for evidence outside El Centro College on Lamar Street in Dallas where a gunman killed five police officers and wounded seven others.

The residence of Micah Xavier Johnson, 25, following the fatal shootings of five police officers on July 8, 2016 in Mesquite, Texas. Johnson has been identified as the suspected sniper in the fatal shooting of five police officers, and injuring seven more at a demonstration held on July 7, 2016 in Dallas, Texas.

Police Officer Katherine Rhodes, right, embraces Officer Yuridia Morales at a memorial for the shooting victims.

From top left counter clockwise, Fermin Betancourt, Damien Betancourt, 10, Destiny Betancourt, 11, and Police Officer Yuridia Morales pay their respects at the memorial for slain Dallas officers.

Dallas police officers comfort each other Friday, July 8, 2016, in Dallas in front of police cars decorated as a public memorial in front of police headquarters, in honor of Dallas police who were killed Thursday.

Dallas Police Chief David Brown pauses at a prayer vigil following the deaths of five police officers last night during a Black Live Matter march on July 8, 2016 in Dallas, Texas.

A Dallas police cruiser sits along Griffin Street near the parking garage, rear left, where an active investigation scene is ongoing, July 8, 2016, in Dallas.

People pray at a faith vigil at Thanks-Giving Square in Dallas, Texas on July 8, 2016, following the shootings during a peaceful protest on July 7 which left 5 police officers dead.

Notes of support and sympathy are taped to a Dallas Police Department squad car Friday, July 8, 2016, outside police headquarters in Dallas. A Black Lives Matter rally in the area the night before turned deadly when a gunman killed five police officers.

People gather in a prayer vigil following the shooting deaths of five police officers last night during a Black Live Matter march on July 8, 2016 in Dallas, Texas.

Community members pray during interfaith prayer event June 8, 2016, in Dallas, for the victims of the shooting that killed 5 police officers and wounded 7 others.

Dallas resident Daniel Bray embraces Emilie Bedell during an interfaith prayer eventon July 8, 2016, in Dallas for the victims of the mass shooting that killed 5 police officers and wounded 7 others.

Ethan Boothe, center, talks to his sons Greyson Boothe, 8, left, and Austin Boothe, 10, right, to explain the significance of the interfaith prayer event held July 8, 2016, for the victims of the shooting that killed 5 police officers and wounded 7 others Thursday night in Dallas.

Dallas police officers stand guard at a road block to the crime scene at El Centro College on July 8, 2016, where a sniper attacked a Black Lives Matter protest Thursday night, killing 5 police officers and wounding 7 others.

Investigators document the crime scene outside El Centro College where a sniper unleashed a barrage of bullets Thursday night in Dallas, Texas, killing 5 police officers and wounding 7 others, during a protest over recent police shootings in Minnesota and Louisiana, on July 8, 2016.

Investigators comb through the crime scene outside El Centro College on July 8, 2016, following Thursday night’s deadly sniper attack in Dallas.

A crime scene investigator looks a shot out windows after a shooting in downtown Dallas, Friday, July 8, 2016.

Police tape is seen July 8, 2016, marking off the area where a shooting took place in downtown Dallas the night before.

Crime scene investigators survey the area after a shooting in downtown Dallas, on July 8, 2016.

Broken glass from windows shot out at a store litter the street downtown Dallas, on July 8, 2016.

Glass shards are exposed on broken a window of El Centro College in downtown Dallas, on July 8, 2016.

A clerk looks at broken windows shot out at a store in downtown Dallas, on July 8, 2016.

Areas of downtown Dallas remain closed Friday, July 8, 2016.

Dallas police officers face protesters July 8, 2016, at Ross Avenue and Griffin Street in downtown after 11 police officers were shot by snipers during a peaceful protest in the Texas city.

A Dallas police vehicle that has a red stain beneath the door is hauled away from the Baylor University Medical Center emergency room July 8, 2016, in the Texas city.

People stand near pollice barricades following the sniper shooting in Dallas on July 7, 2016.

Police stand guard at a barricade following the sniper shooting of police officers in Dallas, Texas, on July 7, 2016.

A Dallas police officer takes a moment as she guards an intersection early July 8, 2016, after snipers shot officers in the Texas city earlier in the night.

President Obama pauses as he speaks on the shooting in Dallas, Texas, on the sidelines of the NATO Summit in Warsaw, Poland on July 8, 2016.

Dallas police detain a driver after several police officers were shot in downtown Dallas, Thursday, July 7, 2016. Snipers apparently shot police officers during protests and some of the officers are dead, the city’s police chief said in a statement.

An unidentified woman and a law enforcement officer reach for each other’s hand as they walk out of the Baylor University Medical Center emergency reception area, early Friday, July 8, 2016, in Dallas.

Dallas Mayor Mike Rawlings, right, talks with unknown persons as he arrives at the emergency room at Baylor University Medical Center, Friday, July 8, 2016, in Dallas. Snipers opened fire on police officers in the heart of Dallas on Thursday night, killing some of the officers.

Police check a car early Friday, July 8, 2016, in Dallas, Snipers opened fire on police officers in Dallas on Thursday night; some of the officers were killed, police said.

Police and others gather at the emergency entrance to Baylor Medical Center in Dallas, where several police officers were taken after shootings Thursday, July 7, 2016.

Dallas police stop a driver in downtown Dallas, Thursday, July 7, 2016, following shootings of police officers. Snipers apparently shot police officers during protests and some of the officers are dead, the city’s police chief said in a statement.

A Dallas policeman keeps watch on a street in downtown Dallas on July 7, 2016 after shots were fired.

People protesting recent police shootings rally in downtown Dallas on July 7, 2016. Later in the evening, shots rang out and the crowd scattered to seek cover.

People rally in Dallas, Texas, on Thursday, July 7, 2016 to protest the deaths of Alton Sterling and Philando Castile. Black motorist Philando Castile, 32, a school cafeteria worker, was shot at close range by a Minnesota cop and seen bleeding to death in a graphic video shot by his girlfriend that went viral Thursday, the second fatal police shooting to rock America in as many days.

A man lays on the ground after yelling “Don’t shoot me” at police during a rally in Dallas, Texas, on July 7, 2016, to protest the police-shooting deaths of Alton Sterling in Louisiana and Philando Castile in Minnesota.