WARSAW, Poland (CBSNewYork/AP) — President Barack Obama said America is “horrified” over the shootings of police officers in Dallas and there’s no possible justification for the attacks.

Obama spoke Friday from Warsaw, Poland, where he’s meeting with leaders of the European Union and attending a NATO summit.

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“I spoke this morning with Mayor Rawlings of Dallas to convey deepest condolences of the American people,” the president said. “I told him that the federal government will provide whatever assistance Dallas may need as it deals with this tremendous tragedy.”

He said justice will be done and he’s asking all Americans to pray for the fallen officers and their families. He also said the nation should express its gratitude to those serving in law enforcement.

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“Today is a wrenching reminder of the scarifies that they make for us,” he said.

Snipers opened fire on police officers in the heart of Dallas Thursday evening, killing five officers and injuring six others during protests over two recent fatal police shootings of black men.

Obama said earlier there was no contradiction between supporting law enforcement and making certain biases in the justice system are rooted out.

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