The President urged Americans to come together in the wake of the attack, which the FBI and other law enforcement officials were trying to piece together in terms of a motive.
"In moments of tragedy and horror, America comes together as one - and it always has," the President said.
"Our unity cannot be shattered by evil," the President added, as he ordered flags at federal buildings to be flown at half-staff in honor of those who died in the gun attack.
The President was joined in his public expression of grief by members of Congress in both parties - but a number of Democrats, who have chafed at a lack of action on gun violence, said it was time to do more than offer 'thoughts and prayers,' and have moments on silence on the floors of the House and Senate.
"Enough is enough," said Rep. Mike Thompson (D-CA). "Congress should come together and establish a Select Committee to end gun violence."
"It's time for Congress to get off its ass and do something," said Sen. Chris Murphy (D-CT).
"The frequency of these awful events — Newtown, Aurora, Orlando, Las Vegas — is striking and must be met with immediate action," said Rep. Rose DeLauro (D-CT).
"Let's once again ban assault weapons," said Sen. Ed Markey (D-MA).
"We must not, as a nation, allow ourselves to become immune to the pain of mass gun violence," said Rep. Steny Hoyer (D-MD).
"To my GOP colleagues, lets work to end this violence," said Rep. David Cicilline (D-RI).
Here is the full statement from President Trump: