Dallas shooting

Speaking to CNN's Don Lemon Monday night, he said that the experience has affected him deeply and was like "this bad movie on an endless loop."

He added: "Going to work has forced me to kind of push it aside temporarily but it continues to break through.

"I'm thinking about the officers and their families and the men that were killed in Baton Rouge and Minnesota last week and I compare my situation to theirs and it's hard for me to focus on myself right now."

He told a memorial service in the city the US must "try to find some meaning amidst our sorrow" and could unite.

His trip came amid mounting racial tensions across the country.

Micah Johnson killed the Dallas officers at a protest held over the recent police shootings of African Americans in Minnesota and Louisiana.

Before he was killed by police, he said he was angry about the shootings.

Meanwhile, protests over excessive police force against black Americans have been held in cities across the US.

The girlfriend of Castile live streamed the incident on Facebook but the video takedown and reuploaded with a warning. The reason given behind these killings is the racial difference that prevails in the society. Maybe it does or doesn’t, but it definitely affects the lives of the people connected to the victims of such cases.

What happened?

In the wake of the shooting of the Dallas police officers Thursday night during a peaceful protest, police cornered the shooter -- Micah Xavier Johnson -- in a parking garage. After an hours-long standoff that included exchanges of gunfire, they used a robot to deliver an explosive that killed the gunman.

Why did they use it?

They said they had received an anonymous threat, two days after the killing of five police officers.

A nearby parking lot was searched for a "suspicious person" but no-one was found. SWAT officers were earlier deployed at the main building.

On Thursday, five white police officers were shot dead by a black man, Micah Johnson, during a protest rally.

The march was against the killing of black men by police. Two deaths this week have led to nationwide protests.

The suspect told police that he was working alone, Police Chief David Brown told reporters.

Five Dallas police officers were killed and seven wounded by gunmen during protests against the shooting of black men by police, authorities say.

Three people are in custody.

Mr Brown said the suspect had been killed when police used explosives placed by a robot to end a tense stand-off in a building where he was holed up.