(CBS News) WACO, Texas - The president was in Waco, Texas Thursday for a memorial for the 14 people who were lost in that catastrophic explosion last week. A procession stretched for miles on the way to an auditorium at Baylor University, where hundreds gathered in a final farewell.
"We may not all live here in Texas, but we're neighbors, too," President Barack Obama said. "We're Americans, too. And we stand with you, we we do not forget, and we'll be there even after the cameras leave. And after the attention turns elsewhere, your country will remain ready to help you recover and rebuild and reclaim your community."
Many of those killed were fighting a fire at a fertilizer storage facility in a town called West. Many homes and businesses were leveled.
Investigators are meticulously sifting through debris to find evidence to explain what caused the fire and explosion at the west fertilizer company.
The blast left a crater 90 feet wide. The remains of some of the volunteer firefighters were found just a few yards away.
This investigation is now focused on the ammonium nitrate stored here. The fertilizer is highly explosive. More than 4,000 pounds of it was used in the Oklahoma City bombing.
Documents filed with the State of Texas last year indicate West Fertilizer Company may have stored more than a half-million pounds of the chemical. Businesses storing more than 400 pounds of ammonium nitrate are required to report it to the Department of Homeland Security, but there is no evidence West Fertilizer filed the paperwork.
Mayor Tommy Muska says his volunteer Fire Department knew the ammonium nitrate was a danger.
"They were trying to put out a fire so it wouldn't be an explosion," he said. "We had the training, we train. Do we have enough training? I'm not sure about that.
Dr. George Smith wants answers, too. Four of the people killed were volunteers in the emergency medical service he founded.
"We go in when other people are running away - we go in. We know that at any time something like this can happen," he said.
Smith was just 250 yards away from the explosion.
"What I'd like to say to the nation is go down to your local fire department or your EMS, shake their hand and tell them thank you," he said. "Because they risk their lives every day for you ... it's important. We need to go give them a hug, shake their hands and tell them thank you."
The owners of West Fertilizer are not commenting on what happened. But in a written statement said they were working closely with the investigating agencies.