NEW YORK (AFP) - Republican presidential contender Donald Trump vowed "strong leadership" Friday (July 8) to what he called worsening race relations after five police officers were killed in Dallas.

Both Trump and Democratic rival Hillary Clinton called off campaign rallies after the sniper attacks Thursday night in Dallas, which followed a spate of police killings of African Americans.

Trump deplored the Dallas attacks as "horrific," but the often bombastic speaker offered a measured statement that also noted the "senseless, tragic" recent deaths of two African American men in Minnesota and Louisiana.

"Our nation has become too divided. Too many Americans feel like they've lost hope," Trump said in a statement.

"Crime is harming too many citizens. Racial tensions have gotten worse, not better. This isn't the American Dream we all want for our children," he said.

"This is a time, perhaps more than ever, for strong leadership, love and compassion. We will pull through these tragedies," he said.

Trump has often played with racial tensions in the past and rose in political prominence by highlighting unfounded conspiracy theories that President Barack Obama, the first African American president, was secretly born in Kenya.

The billionaire populist has made the deportation of undocumented Mexican immigrants the cornerstone of his presidential campaign and has called for a temporary ban on all foreign Muslims entering the United States.

Trump canceled a trip to Miami after the tragedy and Clinton put off a stop in a working-class part of Pennsylvania where she had been due to campaign with Vice President Joe Biden.

"I mourn for the officers shot while doing their sacred duty to protect peaceful protesters, for their families and all who serve with them," Clinton wrote on Twitter.

Before the Dallas attack, Clinton also voiced concern about the deaths of African Americans, saying, "too many young black men and women have been taken from us."