Fourteen people were killed and 200 others were injured in last week's blast at a plant in West, Texas. Most of those killed were first responders who rushed to the scene to battle a blaze.
"This small town's family is bigger now," the president said during a memorial service at Baylor University's Ferrell Center. "To the families, the neighbors grappling with unbearable loss, we are here to say you are not alone. You are not forgotten ... We may not all live here in Texas, but we're neighbors too. We're Americans too, and we stand with you."
Nearly 10,000 gathered for the service, which is more than triple the size of West's entire population of 2,700. The president spoke for 16 minutes, quoting scripture and lauding the men whose flag-draped coffins laid before him.
"When you got to the scene, you forgot fear and you fought that blaze as hard as you could, knowing the danger," Mr. Obama said.
The president has ordered flags at federal and military facilities in Texas to be flown at half-staff in memory of the victims.
At the blast site, investigators from the Bureau of Alcohol, Tobacco, Firearms and Explosives are trying to piece together the events that led to the explosion. Authorities believe it was sparked by the fire, but the cause of the fire is still not known.
The explosion damaged nearly 150 homes in the town of West, forcing many residents to seek shelter in nearby Waco. Residents say they want to rebuild what was lost.
"We definitely want to stay here, this is our home. This is the town we were born and raised in, grew up in our whole lives. It's where all of our memories are, and of course, we want that for our kids too," said West resident Mandy Jores.
Damage to the town is expected to be more than $100 million. Two lawsuits have already been filed against the fertilizer company that runs the plant.