WASHINGTON — A fifth police officer died during a shootout with snipers during a protest against police shootings of black men that also wounded six other officers and a civilian, authorities said.

"It has been a devastating night. We are sad to report a fifth officer has died," the Dallas Police Department wrote on Twitter, with some describing it as a nightmare with seemingly no end in sight.

US President Barack Obama, who is attending a NATO summit in Warsaw, has been briefed on the killing of police officers in Dallas during a protest against police shootings of black men.

"The president has been updated on the shooting of police officers in Dallas. He asked his team to keep him updated on the situation as they get additional information," White House spokesman Josh Earnest said.

"Hurting for Dallas right now," said Alex Morgan, a member of the US national women’s soccer team.

"It seems like we wake up or go to sleep reading more tragedies than not. I want to wake up from this nightmare."

NBA star LeBron James took to Twitter to tell his 31.5 million social media followers that violence won’t solve anything.

"We are all hurting tonight," James tweeted.

"More violence is not the answer. #StoptheViolence."

The American athletes were reacting to chaotic scenes of gun attacks during what was supposed to be a peaceful protest in downtown Dallas, Texas, against perceived police brutality and racial bias.

Police said at least two snipers opened fire ambush style on officers who were on duty for the protest march.

"I want to hope this is all a bad dream...it ain’t," two-time Major League Baseball World Series champion Shane Victorino tweeted.

Chris Iannetta, catcher for the Seattle Mariners, called for an end to shootings on both sides.

"People. Please end the violence. Enough is enough. We are all humans. We all deserve the right to live happily!" he wrote.

Japanese pitcher Yu Darvish has played four seasons with the Texas Rangers and lives in Dallas.

"Pray for my hometown. #prayforDallas," he tweeted. Darvish comes from Japan, which has some of the strictest guns laws in the world.

In 2008, there were just 11 firearm-related homicides in Japan. That compares to over 12,000 in America, which has one of the highest gun-related murder rates in the world.

"Praying for this world my kids gotta grow up in...I’ll die for them, won’t let the streets or the (social) media raise them. That’s on God," tweeted Oklahoma City Thunder player Anthony Morrow.

Spencer Dinwiddie, who played 12 games with the Detroit Pistons this past season, said the killings seem so senseless.

"Whole lotta hate out here...and in the grand scheme of things it’s for no reason," he tweeted.

The Dallas Stars NHL club tweeted: "Deepest sympathies to all those affected in Dallas tonight. Our thoughts and prayers are with DART PD and Dallas PD." — AFP