The weather wasn't cooperating with their efforts: National Weather Service crews surveying the damage in Moore reported rain, half-inch hail and 45-mph winds over the debris field.
The Oklahoma Highway Patrol asked motorists to steer clear of Interstate 35 near Moore to free up lanes for disaster response resources streaming into the area.
And so many people were showing up to volunteer that authorities had to plead with would-be rescuers to stay away.
Path of devastation
The tornado struck at 2:45 pm C.T. on Monday -- only 5 minutes after the first warnings went out, according to the National Weather Service.
Moore residents had about 30 minutes before the massive storm entered the western part of the city, CNN meteorologist Sean Morris said.
Among the many buildings struck by the storm were two schools: Plaza Towers and Briarwood elementaries.
Of the nine children killed by the storm, authorities said seven died at Plaza Towers Elementary School where the tornado ripped the roof off and collapsed walls.
Among the dead is 9-year-old Ja'Nae Hornsby, who was killed at Plaza Towers, her father told CNN's Anderson Cooper.
About 75 students and staff members were hunkered down in Plaza Towers when the tornado struck, CNN affiliate KFOR reported.
At one point, an estimated 24 children were missing from the school, but some later turned up at nearby churches.
On Monday, a father of a third-grader still missing sat quietly on a stool outside. Tears cascaded from his face as he waited for any news.
Even parents of survivors couldn't wrap their minds around the tragedy.
"I'm speechless. How did this happen? Why did this happen?" Norma Bautista asked. "How do we explain this to the kids? ... In an instant, everything's gone."
James Dickens, a gas-and-oil pipeline worker, grabbed his hard had and joined other rescuers at Plaza Towers Elementary School.
"I felt it was my duty to come help," he said Tuesday after a long night of searching.
"As a father, it's humbling. It's heartbreaking to know that we've still got kids over there that's possibly alive, but we don't know."
Moore, and the Oklahoma City region, are far too familiar with disaster. In 1995, 168 people died in the bombing of the Alfred P. Murrah Federal Building in Oklahoma City.
In 1999 and then again in 2003, Moore took direct hits from tornadoes that took eerily similar paths to Monday's storm. The 1999 storm packed the strongest wind speeds in history, Lt. Gov. Todd Lamb said.
"We're a tough state. This is a tough community," Lamb said. "There is hope. We always have hope. We always have faith."
President Barack Obama, pledging whatever federal aid Oklahoma would need, praised teachers who protected their students.
"If there is hope to hold on to -- not just in Oklahoma but around the country -- it's the knowledge that the good people there and in Oklahoma are better prepared for this type of storm than most," he said. "And what they can be certain of is that Americans from every corner of this country will be right there with them, opening our homes, our hearts, to those in need, because we're a nation that stands with our fellow citizens as long as it takes."
More trouble brewing
The storm system that spawned Monday's tornado and several other twisters Sunday isn't over yet.