Obama says America is horrified over Dallas attack

President Barack Obama today said that America is "horrified" by what appears to be a planned sniper shooting targeting police officers in Dallas, and he said there is no justification for the violence.

In a brief statement to reporters, Obama said the investigation into the shooting continues but "what we do know is there has been a vicious, calculated and despicable attack on law enforcement," he said.

Obama called the shooters motives "twisted" and vowed they would be brought to justice.

"There's no possible justification for these kinds of attacks or any violence against law enforcement," Obama said, noting that he had spoken with Dallas Mayor Mike Rawlings and offered his support and condolences.

Obama spoke from Warsaw, Poland, where he is meeting with NATO and European Union leaders. Obama arrived early today shortly before snipers opened fire on police officers, killing five officers and injuring six others during protests over two recent fatal police shootings of black men.

Immediately after landing in Warsaw, and before the shootings, Obama had expressed solidarity with protesters earlier. In those comments, he aired his frustration with what he said were racial disparities in the justice system.

He also argued there was no contradiction between supporting law enforcement and working to see that biases in the criminal justice system are rooted out.

Obama emphasised another part of his message later today. He called the shootings a "wrenching reminder of the sacrifices" that police office make every day.