difference between "happened" and "might have happened"

After a deadly random shooting at Fort Food the other day, President Obama was quoted as saying as follows:

In Chicago, President Obama said that White House and Pentagon officials were following the events closely. “We are going to get to the bottom of exactly what happened,” the president said. “We’re heartbroken something like this might have happened again.”

What does he exactly mean by saying "we're heatbroken somethign like this might have happened again" instead of "We're heartbroken somehting like this happened again?"

Fujibei said:

After a deadly random shooting at Fort Food the other day, President Obama was quoted [STRIKE]as saying[/STRIKE] as follows: [too many 'as']

Click to expand...

He's possibly hedging. One would have to know exactly what he means by "something like this" to answer your question exactly. He cannot say that "something like this" has happened again, because they are still not 'at the bottom of exactly what happened'.
"Something like this" might be "an apparently sane soldier suddenly shooting at his own men in a peaceful environment", but it's not possible to know exactly what is in Obama's mind - and I doubt whether that's coincidental.

Fort Hood, not Fort Food.