An Army veteran “upset about Black Lives Matter” and “recent police shootings” who opened fire Thursday night in Dallas in an attack on police officers has been identified by police as Micah Xavier Johnson.

Five police officers were killed and seven were wounded, officials said. Two civilians were also wounded in the shootings, police said.

Johnson, 25, was killed when a police robot detonated a bomb near him following a standoff that lasted several hours, Police Chief David Brown said Friday at a press conference.

“The suspect said he was upset with white people and wanted to kill white people, especially white officers,” Brown said.

Dallas Mayor Mike Rawlings said Johnson was the lone gunman, though police initially said two snipers positioned themselves in triangulated locations to fire on officers from elevated positions. Rawlings said confusion during the incident led to the belief there were multiple shooters.

“We believe now that the city is safe, and we can move on to healing,” Rawlings said Friday evening.

Homeland Security Director Jeh Johnson said there are no apparent ties to international terrorism.

The gunfire began just before 9 p.m. Thursday while a peaceful rally was held by Black Lives Matter in response to recent controversial police killings of black men in Louisiana and Minnesota.

The gunman was then cornered in El Centro College in downtown Dallas.

Police said at least 12 officers fired their weapons during the incident.

This post will be updated as more information is released. Here’s what we know so far about Johnson and the shootings:

Warning: Some of the videos below may contain graphic content.

1. The Former Soldier Told Police He Was Not Affiliated With Any Groups & He ‘Did This Alone’

After the shootings in downtown Dallas, the gunman, identified as Micah Xavier Johnson, 25, holed himself up inside El Centro College in the downtown area of the city, Dallas Police Chief David Brown said at a press conference.

Johnson was armed with a SKS semi-automatic assault rifle and a handgun, CBS News reports. He was wearing body armor.

He told police he was “not affiliated with any groups,” and he said he “did this alone,” the chief said.

Sources told the Los Angeles Times that Johnson has no ties to terror groups and no known criminal history. He has lived in the Dallas area and has family members living in Mesquite, Texas, east of Dallas, the newspaper reports, citing federal law enforcement sources.

A black SUV was found at the scene registered to Delphene Johnson, who is Micah Johnson’s mother, according to Facebook posts and public records, NBC Dallas-Fort Worth reports. Live helicopter video from the news station showed police at her home in Mesquite.

Johnson served in the U.S. Army Reserve, investigators said.

Johnson told police negotiators the “end is coming” and said he wanted to “kill more” officers, according to Brown.

Police said after several hours of negotiating, with intermittent exchanges of gunfire, the suspect was killed by a robot who detonated a C-4 explosive.

“We tried to negotiate for several hours, negotiations broke down, we had an exchange of gunfire with the suspect,” Brown said. “We saw no other option but to use our bomb-robot and place a device on its extension for it to detonate where the suspect was. Other options would have exposed our officers to grave danger. The suspect is dead a result of detonating the bomb.”

Mayor Mike Rawlings said, “He had a choice to come out and we would not harm him, or stay in and we would. He picked the latter.”

The suspect did not shoot himself, despite reports, Brown said.

“He wanted to kill officers, and he expressed killing white people, he expressed killing white officers,” Brown said. “He expressed anger for Black Lives Matter. None of that makes sense, none of that is a legitimate reason to do harm to anyone, so the rest of it would just be speculating on what his motivations were. We just know what he said to our negotiators.”

FOX News airs footage showing two Dallas police officers downJuly 7, 2016: At least two police officers were injured in a shooting near a Dallas protest Thursday evening. FOX News Channel carried live footage from the scene as police worked to establish a security perimeter around two injured officers. Video: KDFW / FOX News Channel 2016-07-08T03:03:07.000Z

While he was barricaded in the hotel, the suspect told police there were bombs planted “all over” downtown Dallas, the city’s police chief said at a press conference.

Police have not said if any bombs or suspicious items have been found.

“He said we will eventually find the IEDs,” Brown said.

The shooting came a year and a month after a man angry at police opened fire on the Dallas Police headquarters. He fired several shots at the building, but no one was injured. The man, James Boulware, was driving an armored van and was later chased down by police. He was killed during a standoff.

Boulware also claimed he had planted bombs in downtown Dallas.

Read more about Micah X. Johnson in Spanish at AhoraMismo.com:

2. He Had Connections to ‘Black Separatist Hate Groups’ on Facebook

Micah Johnson’s now-deleted Facebook page provides few details about his life. In May, he posted a “Black Power” poster, one of the few images on his page:

His cover photo is the Pan-African flag.

He liked pages connected to Elijah Mohammed, the founder of the Nation of Islam, and also like The New Black Panther Party and the Black Riders Liberation Party.

The Southern Poverty Law Center calls the three organizations “black separatist hate groups,” according to its Hatewatch blog:

NBPP was formed in Dallas, and its leaders have long expressed virulently anti-white and anti-Semitic opinions. Its leaders have blamed Jews for the 9/11 terrorist attacks and for the slave trade. The late former party chairman Khalid Abdul Muhammad once said, ‘There are no good crackers, and if you find one, kill him before he changes.’ A document on the NBPP website titled “The Nationalist Manifesto” claims that white men have a secret plan to commit genocide against the non-white races. It also refers to black people who condone mixed-race relationships as the ‘modern day Custodians [sic] of Uncle Tom’s Cabin.’

The Daily Beast said the African American Defense League, another group liked by Johnson, posted on Facebook after the shootings, “ATTACK EVERYTHING IN BLUE EXCEPT THE MAIL MAN, UNLESS HE IS CARRYING MORE THAN MAIL.”

On Saturday, Johnson posted a video of people slaughtering dolphins to a Black Panther Facebook page, writing, “Look at the joy on their faces. Why do so many whites (not all) enjoy killing and participating in the death of innocent beings?,” according to CBS News.

The SPLC called the shootings an act of domestic terrorism in a statement from its president, Richard Cohen:

We condemn the racially motivated killings of law enforcement officers in Dallas and mourn the loss of life. This was an act of domestic terrorism,Racial tensions are extremely high in this country – not just in the wake of the most recent highly visible killings of black men by law enforcement but in the overheated rhetoric of our politics and hate deliberately stoked from all corners. Our communities need healing. Until a gunman motivated by hate fired a shot, the protest was a peaceful one in a city that serves as a model for law enforcement reform. We must not allow this act of violence to lead to more violence and more hate.

Johnson posted a photo with Professor Griff, a rapper and member of the group Public Enemy, taken at what appears to be an autograph signing, in April. His only other photo is a Doctor Who wallpaper. His birthday was July 2.

The Dallas Police highlighted Johnson’s association with Professor Griff in a press release Friday afternoon.

“The suspect’s Facebook account included the following names and information: Fahed Hassen, Richard GRIFFIN aka Professor Griff, GRIFFIN embraces a radical form of Afrocentrism, and GRIFFIN wrote a book A Warriors Tapestry,” police said. No other context was provided in the press release.

Griff has responded on Twitter, saying, “The police and FBI have been watching me and tapping my phone they know who I talk too, I DO NOT KNOW THE SHOOTER. … I do not advocate killing Cops.”

Johnson’s sister posted on Facebook on Friday after his name was made public, “I keep saying its not true…my eyes hurt from crying. Y him??? And why was he downtown smh.

“Please out of respect for my family. If you following the news and know whats going on, I’m not talking to anyone and please keep your comments thoughts respectful,” she wrote. “The news will say what they think but those that knew him know this wasn’t like him. Only close family can call me. This is the biggest loss we’ve had.”

3. Police Say Johnson Was a ‘Loner’ Who Had ‘Bomb Making Materials, Ballistic Vests, Rifles’ & Ammo in His Home

Police said Johnson has been described as a “loner.”

“This was a well-planned, well-thought-out, evil tragedy,” Dallas Police Chief David Brown said.

“During the search of the suspect’s home, detectives found bomb making materials, ballistic vests, rifles, ammunition, and a personal journal of combat tactics,” police said in a press release. “Detectives are in the processing of analyzing the information contained in the journal.”

Mayor Mike Rawlings said the gunman was a “mobile shooter” and had written manifestos on how to “shoot and move, shoot and move, and he did that,” causing confusion during the shooting. But police say he acted alone.

Authorities said they will still be investigating to see if anyone knew about the gunman’s plans or had any other role in the incident. Federal, state and city police agencies are also determining what the shooter did leading up to the shooting, and are looking into his background.

Brown earlier said they want to ensure “that everyone associated with this tragedy is brought to justice. … We won’t expand on any further on what other suspects we have interviewed or looked at or their status until we get further into this investigation and get closer to a conclusion of who are all involved.”

Brown said, “I’m not going to be satisfied until we turn over every stone. … We’re not satisfied that we’ve exhausted every lead. And we’re not going to be satisfied until every lead is exhausted. So if there is someone out there that was associated with this, we will find you and we will prosecute you and we will bring you to justice.”

Police said two people were spotted getting into a Mercedes in downtown Dallas carrying camouflage duffle bags, the police chief said. The car was found by police and stopped on the highway. The people in the car were taken into custody. The chief said a woman was also arrested near El Centro College.

They were not cooperating with investigators, officials said.

But sources told CBS News the three people detained were not connected to the shooting.

One man who was marching during the protest, Mark Hughes, was incorrectly identified by police as a “person of interest” in the shooting, and his photo was distributed on Twitter by the department. Hughes was open carrying a rifle, which is legal in Texas, to exercise his Second Amendment rights, but he turned over the gun to a police officer after the shooting began so he would not be mistaken as a suspect. That moment was caught on video:

Facebook video of DPD's original person of interest, handing over his weapon to authorities Via facebook live videohttps://t.co/hDmeV6T4sz — Mike Leslie (@MikeLeslieWFAA) July 8, 2016

The man later turned himself in to police after his photo was distributed across social media and on national television. He was released after being questioned.

Police said a 25-year-old man was arrested at the scene on unrelated weapons charges. It is not clear if he was one of the three people described as being possible suspects.

4. Johnson Was in the Army Reserves & Served in Afghanistan

A Department of Defense official told The Daily Beast that Micah Johnson was a private first class in the Army Reserves. He was part of the 284th Engineering Company, which is based in Santa Fe, New Mexico.

The official said Johnson served in Afghanistan.

He was a carpenter and masonry specialist, CNN reports. It is not known if he had advanced firearms training, DOD officials told CNN.

Johnson served from March 2009 to April 2015. He was deployed to Afghanistan from November 2013 to July 2014.

5. Police Took Part in the Planning of the Peaceful Rally & March, the Chief Says

The shootings came during a peaceful rally and march in response to two controversial police shootings of black men that occurred this week. The rally began at 7 p.m. and was set to end at 9 p.m. The shooting occurred just before 9 p.m.

Alton Sterling was fatally shot by two officers in Baton Rouge, Louisiana on Tuesday. A day later, Philando Castile was killed by police during a traffic stop in Falcon Heights, Minnesota. Parts of both shootings were caught on videos that spread quickly across social media. Investigations into both those shootings are ongoing and no officers have been charged.

Dallas Police Chief David Brown said he and others in the police department participated in the planning of the rally.

Something people should understand nationally — BLM & Dallas PD have respect for each other. DPD was protecting marchers. Snipers did this. — Mike Leslie (@MikeLeslieWFAA) July 8, 2016

Officers were posing for pictures with marchers and the mood was peaceful and light, officials said.

Demonstration in #Dallas @ Belo Garden Park pic.twitter.com/IUx5IaERSB — Dallas Police Depart (@DallasPD) July 8, 2016

#Dallas police officers maintain traffic control to ensure the safety of the demonstrators. pic.twitter.com/wocOuXqj0g — Dallas Police Depart (@DallasPD) July 8, 2016

Police have released no evidence that the planners of the protest were involved in the shooting.

“Police officers are guardians of this great democracy, the freedom to protest, the freedom of speech, the freedom of expression, all freedoms we fight for with our lives, it’s what makes us who we are as Americans,” Brown said. “So we risk our lives for those rights, so we won’t militarize our policing standards, but we will do it in a much safer way every time.”

Brown said they had an “adequate” amount of officers and were doing the right thing to shut down traffic and protect people’s right to protest.

“We are not going to let a coward who would ambush police officers change our democracy. We’re not going to do it. Our city, our country is better than that,” Brown said.

Four of the officers killed are from the Dallas Police Department. The fifth victim, Officer Brent Thompson, worked for the Dallas Area Rapid Transit (DART) authority’s police department.

A second victim was identified by family members as Dallas Officer Patrick Zamarripa.

The other officers have not yet been identified publicly and Brown said they are working to notify families of the victims.

One wounded officer has been identified as DART Officer Misty McBride. She is expected to survive.

“Some of the bravest men and women you ever want to be associated with,” Brown said about the Dallas and DART police officers who responded to the shooting. “You see video footage after video footage of them running toward gunfire from an elevated position with no chance to protect themselves. And to put themselves in harms way to make sure citizens can get to a place of security.

“So please join me in applauding these brave men and women who do this job under great scrutiny, under great vulnerability. Who literally risk their lives to protect our democracy. We don’t feel much support most days, let’s not make today most days. Please, we need your support to be able to protect you from men like these who carried out this tragic, tragic event. Pray for these families,” Brown said.