Federal investigators have not uncovered the cause of the explosion that killed 14 people and injured about 200 others. But 911 tapes captured the initial chaos following the massive blast.
"There was, um some sort of explosion at our house. All the windows on the (inaudible) of the house are completely blown in. The walls, part of it is blown off," one caller said.
"Listen to me. My ambulance station just completely exploded. I've got a nursing home, an ambulance station, and a (inaudible). I need as many East Texas trucks as you can send this way," a second caller said.
Residents in a certain zone were allowed to return to their homes Saturday but still face strict curfews.
Five days after the massive blast, some students attended class in trailers behind damaged school buildings, while others were bused out of the city to once-abandoned campuses. Students up to sixth grade were dropped off at West Elementary School, which was outside the immediate blast zone.
Some parents took the day off to walk or drive their children to school. Classmates who hadn't seen each other for a few days talked and laughed - with dozens of reporters chronicling their arrival.
"I'm just glad to get back to our routine," said 14-year-old Sofia Guerra, who sitting in the car with her mother, Erika, as they dropped her sister off at West Elementary School. "We don't know what to expect."
Fire officials are scheduled to hold a memorial service at Baylor University on Thursday in honor of the six volunteer firefighters who died. Four emergency medics were also among the dead.
Nearly 70 federal and state investigators are still trying to determine what caused the fire that set off the explosion. Authorities said they are conducting a "slow and methodical" search of the site, but there are no signs of criminal intent.
The Associated Press contributed to this report.