Obama Vows to Protect Soldiers in Fort Hood Tribute

President Barack Obama vowed to do more to protect U.S. soldiers on Wednesday as he paid a somber tribute to victims of last week's Fort Hood shooting, the second gun rampage at the Texas military base in five years.

Speaking before the families of three soldiers killed by a comrade who took his own life during the April 2 shooting, Obama referenced the 2009 massacre at the base which claimed 13 lives.

"Part of what makes this so painful is that we've been here before," Obama said.

"This tragedy tears at wounds still raw from five years ago. Once more soldiers who survived foreign war zones were struck down here at home, where they're supposed to be safe," he added.

Military investigators say they may never know what triggered army specialist Ivan Lopez to embark on last week's shooting, which also left 16 people injured.

Completely eliminating every security risk from a base the size of Fort Hood may not be possible, Obama said.

"But as a nation, we can do more to help counsel those with mental health issues, to keep firearms out of the hands of those who are having such deep difficulties," he said.

"As a military, we must continue to do everything in our power to secure our facilities and spare others this pain.

"As commander-in-chief, I'm determined that we will continue to step up our efforts -- to reach our troops and veterans who are hurting."

Obama advocated tighter regulation of firearms after the December 2012 Newtown school massacre which left 26 people dead, but did not reference the broader issue of gun control in his remarks at Fort Hood on Wednesday.