"I also direct that the flag shall be flown at half-staff for the same length of time at all United States embassies, legations, consular offices, and other facilities abroad, including all military facilities and naval vessels and stations," the statement said.
On August 5, six persons were killed and three critically injured when a gunman opened fire inside a gurudwara in Wisconsin as the congregation was making preparations for Sunday morning prayers.
Meanwhile, the US's move to honour victims of the shooting incident was welcomed by the Sikh Americans.
"This is a kind gesture by the leader of our nation. It certainly sends a powerful signal to the world that this nation mourns the Sikh victims who have been killed in a dastardly acts of violence motivated by hate and prejudice," Rajwant Singh, chairman of the Washington-based Sikh Council on Religion and Education, said.
"Ordering the flying of US flags at half-staff at the White House and all buildings representing the US government is a great way to honour the victims and it represents the collective spirit of this nation," he said.
"It conveys the strong message that this is an American tragedy not just a Sikh tragedy. We also pray for the police officers who put their lives in danger to save others," Singh said.