The U.S. flag is seen at half-staff at the White House in Washington D.C., the United States, Oct. 28, 2018. U.S. President Donald Trump has ordered flags at federal buildings throughout the country to be flown at half-staff in "solemn respect" for the shooting victims at a Pittsburgh synagogue. At least 11 people were killed and six others injured after a gunman opened fire Saturday morning inside a synagogue in Pittsburgh, U.S. state of Pennsylvania. (Xinhua/Liu Jie)