Mike Rawlings, Mayor of the city of Dallas, says authorities believe that Micah Johnson, the man accused of killing five police officers in a gun attack during a protest rally in Dallas, acted alone and that the city is now safe.

Bomb-making material, rifles and a combat journal were found at the home of Johnson, who was himself killed.

Johnson was a member of the US army but had been sent home from Afghanistan after being accused of sexually harassing a fellow soldier and was later “discharged honourably”.

Three other suspects were arrested after the shootings but no details have been released about them.

The Dallas protest was against the killing of black men by police, and similar rallies drew thousands across many US cities on Friday.

The demonstrations followed the police killings of Philando Castile in Minnesota and Alton Sterling in Louisiana.

A number of gun attacks on police officers and civilians have occurred in other parts of the US in the aftermath of the deaths in Minnesota and Louisiana.

In the Georgian state capital, Atlanta, on Friday evening, thousands marched in protest at the recent police shootings but although roads were blocked off the demonstration remained peaceful.

Protests against police killings were also held in other cities including Houston, New Orleans and San Francisco. In Baton Rouge, Louisiana, protesters chanted “no justice, no peace, no racist police”.

There have been some arrests at the rallies, but again they were peaceful.

Leaders of the Black Lives Matter organisation have condemned the Dallas killings but say planned marches, including a “Weekend of Rage” in Philadelphia, will go ahead.