The United States is reeling from a sniper ambush that killed five police officers and wounded seven other officers Thursday night in Dallas.
The officers were providing security for a peaceful protest called after two African-American men were killed by police officers in separate incidents this week.
There was a swift outpouring of emotional reaction from political leaders, with Democrats and Republicans calling for healing and unity.
President Barack Obama had just arrived in Warsaw, Poland, for a NATO summit, but reacted swiftly to the tumultuous events happening back home, saying his team had kept him briefed.
“What we do know is that there has been a vicious, calculated and despicable attack on law enforcement. Police in Dallas were on duty, doing their jobs, keeping people safe during peaceful protests," he said.
The president added: “I believe that I speak for every single American when I say that we are horrified over these events, and that we stand united with the people and the police department in Dallas.”
At the U.S. Capitol, Republican House Speaker Paul Ryan was visibly shaken, putting his hand to his mouth before he spoke on the House floor.
“We are all stunned by the events last night in Dallas. We are all outraged. An attack on the people who protect us is an attack on all of us. Our hearts are with the Dallas Police Department," Ryan said.
"Our hearts are with the victims, and especially with their loved ones. They wear the badge, too. I know that to be a cop's wife or a cop's husband is to prepare for the worst, but who could fathom such horror as this," he added.
Ryan went on to appeal for unity in the face of frequent shootings: “There will be a temptation to let our anger harden our divisions. Let’s not let that happen. There’s going to be a temptation to let our anger send us further into our corners. Let’s not let that happen. That script is just easy to write — it’s too predictable.
"Let’s defy those predictions. A few perpetrators of evil do not represent us. They do not control us. The blame lies with the people who committed these vicious acts, and no one else," he said. "And as the president rightfully said, justice will be done. We also have to let the healing be done as well. This has been a long week for our country. It’s been a long month for America. We have seen terrible, terrible senseless things."
Black Caucus speaks out
Members of the Congressional Black Caucus spoke at a news conference that had originally been arranged to call for action after two African-Americans who were killed by police in separate incidents this week that triggered outrage after social media video captured international attention.
CBC Chair G.K. Butterfield called for Congress to stay in session and hold a vote on legislation to reduce gun violence, warning if Congress again fails to act, “it could be a long, hot summer.”
Another CBC member, civil rights icon Congressman John Lewis, took to Twitter to vent his emotion:
A number of other lawmakers also expressed their condolences and concern to police officers across the country who are impacted by this new level of threat.
The two leading presidential candidates, Democrat Hillary Clinton and Republican Donald Trump, canceled their campaign appearances and put out statements on Twitter.
"I mourn for the officers shot while doing their sacred duty to protect peaceful protesters, for their families & all who serve with them. –H," Clinton tweeted.
"Prayers and condolences to all of the families who are so thoroughly devastated by the horrors we are all watching take place in our country," Trump tweeted.