US President Barack Obama and first lady Michelle Obama pay their respects to the dead soldiers at the conclusion of memorial service at Fort Hood in Killeen Texas April 9, 2014. Last week, Army Spc. Ivan A. Lopez killed three and injured 16 others at Fort Hood before taking his own life. The shooting was the second deadly rampage at the base, one of the largest US Army posts in the country, in five years. It raised questions about protecting soldiers at home and caring for troops battling mental illness, such as Lopez. [Photo/Agencies]

HOUSTON - US President Barack Obama attended a memorial service and offered public condolences Wednesday at the US Army post of Fort Hood in Texas where a shooting spree last week left four soldiers dead and 16 others wounded.

Obama and his wife Michelle Obama arrived late Wednesday morning at the sprawling military installation where flags were lowered to half-staff in honor of the victims in the shooting.

"For you, for your families, no words are equal to your loss. We are here on behalf of the American people to honor your loved ones and offer whatever comfort we can," said the president in a somber tone to the Fort Hood community.

Reminding the audience of another deadly rampage, Obama said: " This tragedy tears a wound still raw from four years ago."

This is Obama's second visit to the military base to mourn a tragedy. On Nov 5, 2009, Army psychiatrist Nidal Malik Hasan opened fire at a soldier readiness center in Fort Hood. The shooting left 13 people dead and more than 30 others wounded. It was the deadliest attack on a domestic military installation in US history.

Last Wednesday, Ivan Lopez, an Army truck driver, opened fire in three separate buildings at the post, killing three people and wounding 16 others before committing suicide. Authorities said the soldier, who was being treated for mental health issues, had verbal altercations with his seniors regarding a request for leave just before the shooting.