UPDATED: Sniper shoots 12 police officers, 5 dead; suspect claims he wanted to 'kill white people, especially white officers'

UPDATED 5:30 p.m. Central

DALLAS (Christian Examiner) – Twelve police officers were shot and five killed in an attack by a gunmen following a Black Lives Matter rally in downtown Dallas Thursday night. A civilian was also wounded.

The gunman, identified by police as Micah Xavier Johnson, 25, opened fire around 9 p.m. as protestors were leaving the rally near Belo Garden, but the incident moved through the streets and around several buildings.

The site is two blocks away from Dealey Plaza, where President John F. Kennedy was assassinated.

Dallas Police report that three other suspects are in custody following the attack, but they are reportedly "uncooperative." Initially, it was reported that the shooter took his own life as police closed in, but today Dallas Police Chief David Brown said SWAT officers deployed a robot with a "bomb" attached to kill the suspect.

Brown also said in a press conference that police had cornered the suspect and negotiations had failed to resolve the situation.

"The suspect said he was upset about Black Lives Matter. The suspect said he was upset about recent police shootings. The suspect stated he was upset at white people. The suspect stated he wanted to kill white people, especially white officers," Brown said.

Brown also said that suspect claimed he was not affiliated with any other groups and that he acted alone. 

Johnson also told police he had placed bombs across the city, but police, along with FBI and ATF agents, searched the area for possible improvised explosive devices after the shooting. None were found after two sweeps of the area.

News cameras from the FOX and NBC affiliates were on scene already when the shooting began. Video showed police officers lying on the ground and hiding behind police cars. Police could also be seen running to the scene and evacuating civilians and news crews.

Another video, released on the Internet, showed a Dallas police office engaging the gunman from behind a stone column. The officer apparently shot the suspect who was wearing body armor. The gunman returned automatic fire and shot the officer. He then stood over the officer and executed him.

Police early on circulated a picture of a "person of interest" in the shooting. In the picture, Mark Hughes had a rifle slung on his shoulder (which is legal in Texas). But the brother of the man whose picture was being shown said his brother gave his rifle to a police officer as soon as the shooting started, which a video later confirmed. He was also on the street level. The shots came from an elevated position in El Centro College's parking garage. That man has since been released and cleared.

However, police stopped and arrested three occupants of a black Mercedes that was seen fleeing the scene at a high rate of speed after an occupant was observed throwing a camouflaged duffle bag in the trunk.

Johnson was a U.S. Army Reserve veteran and had served in Afghanistan. It is assumed his assault was retaliation for the recent deaths of several black men – Alton Sterling in Louisiana and Philando Castile in Minnesota – at the hands of police.

Sterling was shot at point blank range during a ground struggle with two police officers in a convenience store parking lot in Baton Rouge. Castile was shot in his car after, it is alleged by his girlfriend, he informed the officer he had a concealed weapon and reached for his wallet to show the officer his license.

Castile's girlfriend filmed the aftermath of the shooting.

Dallas Mayor Mike Rawlings this morning thanked the emergency personnel and police who responded to the area. But, Rawlings said, he would not answer any questions about the suspects in the shooting until later in the investigation.

Chief Brown also refused to answer questions about the number of suspects, indicating it was important to keep the suspects "guessing." However, Brown said he an important message to convey.

"We are heartbroken. There are no words to describe the atrocity that occurred to our city. All I know is that this must stop – this divisiveness between our police and our citizens," Brown, who was born and raised in Dallas, said.

"You see them [the officers] in video after video running toward the gunfire from an elevated position with no chance to protect themselves to make sure citizens can get to a place of safety."

"We don't feel much support most days," Brown said. "Let's not make today 'most days.'"

President Barack Obama called Mayor Rawlings and expressed his condolences.

He also issued a statement from Poland calling the attack "vicious, calculated and despicable."

"Let's be clear, there is no possible justification for these kinds of attacks or any violence against law enforcement officers," Obama said. "Anyone involved in these senseless murders will be held accountable and justice will be done."

He said police were "doing their jobs keeping people safe during a lawful protest."

Texas Gov. Greg Abbott said in a brief statement that the thoughts and prayers of the people of Texas are with the Dallas law enforcement community, as well as Dallas Area Rapid Transit police. He cut short a trip out of state to return to Texas.

Dallas Area Rapid Transit identified its slain officer as Officer Brent Thompson, 43, who had been on the force since 2009. He had also worked as a private security contractor in Iraq and Afghanistan.

Dallas Police have yet to release the names of the four officers it lost in the shooting.