The US President Barack Obama has described the Dallas shooting as 'a vicious, calculated and dispicable attack on law enforcement'.
Five police officers were shot dead by snipers firing from above, during a Black Lives Matter rally against the fatal shooting of two black men by police this week.
Six other officers were injured and three suspects are being held.
A fourth suspect reportedly died after shooting himself.
Barack Obama says he's horrified by these events, and there is no possible justification for what happened.
