The incident began on Sunday morning with shots being fired at a petrol station on Airline Highway in Baton Rouge.
Sine the shooting death of Alton Sterling by Baton Rouge police earlier this month, the department has anxious about credible threats against its officers. "So much chaos. So much is happening", said Sterling, 25.
And: "Everyone right now [needs to] focus on words and actions that can unite this country rather than divide it further".
Mr Sterling, 37, was pinned to the ground and shot in the chest outside a convenience store in Baton Rouge on July 5, sparking protests across the nation.
The man was carrying an AR-15 assault rifle and wearing a ski mask, Vancel said.
The gunman "looked up and he saw me". All three were married and had family.
Louisiana State Police Superintendent Colonel Mike Edmonson told reporters the gunman behind the shooting - widely identified by USA media as Gavin Long, 29 - was killed and there are no suspects at large. He said all officers responding to emergency calls will have backup.
In Kansas City, police cordoned off streets within a block or more of the house where Long lived in a working-class neighborhood of mostly black residents. He was reported by other media to have been 29 years of age and black.
"I'm exhausted physically and emotionally". Long joined the Marines in 2005, became a sergeant in 2008 and was honorably discharged in 2010, the New York Times reports.
A police spokesman said in a press conference that the gunman was believed to have acted alone.
"We do not have an active shooter scenario in Baton Rouge", said Mr Edmonson.
Three more police officers were wounded in the shootout, with one of them in a critical condition in a local hospital.
Sheriff Sid J. Gautreax said law enforcement's "number one priority is the safety of our community", and "with God's help, we'll get through this".
His former partner said Sunday Jackson was "stressed out and depressed" by the recent shootings in Baton Rouge and Dallas, according to NBC News.
Mayor Rogero and Police Chief David Rausch released a joint statement Sunday afternoon on the deadly shootings.