Official White House Photo by Pete Souza

FORT MYERS, Fla. - A somber President Obama paid tribute this morning to the victims of the Colorado shooting, telling supporters the tragedy serves as a reminder that "life is very fragile."

"Our time here is limited and it is precious. And what matters at the end of the day is not the small things, it's not the trivial things, which so often consume us and our daily lives. Ultimately, it's how we choose to treat one another and how we love one another," he said.

The president was in Fort Myers for a previously scheduled campaign stop but cut the event short to focus on the deadly shooting instead.

"I am so grateful that all of you are here. I am so moved by your support. But there are going to be other days for politics. This, I think, is a day for prayer and reflection," he said.

Obama was about to start the second day of his campaign tour through the key battleground state of Florida, when he was informed early this morning of the overnight shooting at the Aurora, Colo., movie theater.

Read more about the Aurora theater shooting here.

Upon learning the news, the president said he thought of his own two daughters.

"My daughters go to the movies. What if Malia and Sasha had been at the theater, as so many of our kids do every day? Michelle and I will be fortunate enough to hug our girls a little tighter tonight, and I'm sure you will do the same with your children," he said. "But for those parents who may not be so lucky, we have to embrace them and let them know we will be there for them as a nation."

Get more pure politics at ABC News.com/Politics and a lighter take on the news at OTUSNews.com

The president vowed whoever is responsible "for this heinous crime" would be brought to justice and said the government would take "every step possible" to ensure the safety of all Americans.

"We may never understand what leads anybody to terrorize their fellow human beings like this. Such violence, such evil is senseless. It's beyond reason," he said.

"While we will never know fully what causes somebody to take the life of another, we do know what makes life worth living," he continued. "The people we lost in Aurora loved and they were loved. They were mothers and fathers; they were husbands and wives; sisters and brothers; sons and daughters, friends and neighbors. They had hopes for the future and they had dreams that were not yet fulfilled."

For continuing coverage on Tragedy in Colorado: The Batman Massacre, tune in to "World News," "20/20? and "Nightline."