President Barack Obama on Sunday ordered flags at government buildings and public grounds to be lowered to half-staff following the early morning massacre at a gay bar in Orlando, Florida.

The decision came hours after what officials are calling the deadliest mass shooting in U.S. history, which has so far claimed 50 lives and injured 53 other people. The gunman has been identified as Omar Mateen, a U.S. citizen who entered the Pulse nightclub armed with an AR-15 military-style assault weapon and a handgun.

Obama released the proclamation moments before delivering a brief address at the White House in which he called the shooting an “act of terror and an act of hate.”

“This could have been any one of our communities,” the president said. “As a country, we will be there for the people of Orlando, today, tomorrow, and all the days to come.”

Flags will fly at half-staff until sunset on Thursday.

Read the entire text of Obama’s proclamation below:

As a mark of respect for the victims of the act of hatred and terror perpetrated on Sunday, June 12, 2016, in Orlando, Florida, by the authority vested in me as President of the United States by the Constitution and the laws of the United States of America, I hereby order that the flag of the United States shall be flown at half-staff at the White House and upon all public buildings and grounds, at all military posts and naval stations, and on all naval vessels of the Federal Government in the District of Columbia and throughout the United States and its Territories and possessions until sunset, June 16, 2016. 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. 

IN WITNESS WHEREOF, I have hereunto set my hand this twelfth day of June, in the year of our Lord two thousand sixteen, and of the Independence of the United States of America the two hundred and fortieth.