Attorney General Loretta Lynch on Friday called the attack in Dallas an "unfathomable tragedy."
"This has been a week of profound grief and heartbreaking loss," Lynch said.
Her comments come after at least one attacker shot 12 police officers, five fatally, during a Thursday night protest over deadly police shootings of black men elsewhere. The attorney general said she was "heartbroken at this loss" and expressed her gratitude for the "difficult and dangerous work [officers] do every day to keep our streets safe and our nations secure."
In the wake of these deaths, Lynch said that "Americans across the county are feeling a sense of helplessness, of uncertainty and of fear."
"These feelings are understandable and they are justified. But the answer must not be violence. The answer is never violence. Rather, the answer must be action: calm, peaceful, collaborative and determined action," she said.