On the night of July 7, 2016, a sniper opened fire in downtown Dallas, Tex., shooting to death Dallas Police Senior Cpl. Lorne Ahrens, Officers Michael Krol and Patrick Zamarripa, Sgt. Michael Smith and Dallas Area Rapid Transit Officer Brent Thompson.

The deadly attack was "well planned," then Police Chief David Brown said at the time .

By the next morning, residents started arriving at police headquarters, to leave flowers, teddy bears and other tributes and at midday on July 8, 2016, hundreds of people packed Thanks-Giving Square Park in downtown Dallas for a time of prayer, music, tears and tributes.

Afterward, people started lining up to hug the officers stationed there to direct traffic or otherwise assist. The spontaneous display of appreciation went viral, and this Facebook Live video taken that day has been viewed more than 38 million times:

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The shooting suspect, Micah Xavier Johnson, 25, was killed after negotiations with authorities failed and a shootout began. A bomb robot ended the standoff.

"He wanted to kill officers. And he expressed killing white people, killing white officers, he expressed anger for Black Lives Matter," Brown said at a news conference at the time .

MORE: What we know about shooting suspect Micah Xavier Johnson

Brown is now an author and on-air contributor for ABC. He retweeted his former department's message in tribute a year after the shootings:

Texas Gov.

Greg Abbott

turned the governor's mansion in Austin into a memorial site in remembrance:

At the downtown Dallas service the day after the shootings, Park Cities Baptist Church Pastor Jeff Warren and Bryan Carter, senior pastor of Concord Church, were among the clergy gathered to offer words of sustenance to a grieving city.

A few days after the shootings, friends and relatives of Brent Thompson, one of the fallen officers, gathered in Corsicana, a town of 25,000 about an hour south of Dallas, to say goodbye.

"Law enforcement is under stresses today unlike we've ever experienced," said  Navarro County Sheriff Elmer Tanner, one of several law enforcement officials who spoke that night.

"I've been a law enforcement officer in this community for over 28 years," he said.  "I have never in my life been touched in a manner that I was in bringing our fallen brother home to our city. The outpouring and showing of love – it was a sight to behold and a fitting tribute to such a fine young man that's gone too early."

 Mourners arrive at a service for fallen officer Brent Thompson in Corsicana, Tex. on July 10, 2016. Photo: Jennifer Brett

Credit: Jennifer Brett

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Credit: Jennifer Brett