Hand over her mouth, Michelle Whitehead stared at the heap of rubble left by the deadliest single tornado since 1947.

“I’m just trying to make sure the people I love are still alive,” she said. “I just can’t believe this.”

Nor could others in this gritty community of 50,000 two days after a vicious twister shredded homes, schools, hospitals and businesses.

At least 123 people were killed, with the toll expected to go higher in light of an announcement that 1,500 people were reported missing. More than 700 were injured, many seriously.

Keith Stammer with the Jasper County Emergency Management Office said the missing tally could include many who have not let relatives known they are safe.

Others, he added, could be patients in hospitals or simply left town in advance of the Sunday dinner-time tornado that struck with little warning.

Seventeen people were pulled alive from the splintered remains. Missouri Gov. Jay Nixon said rescue officials report still others may remain trapped.

“We believe there are more folks alive under the rubble and we’re trying to reach them,” said Nixon.

Rescue crews used specially trained dogs, construction cranes and National Guardsmen to sift through the devastation that wiped out one-third of the city.

Officials gave no estimate of overall damage, except to say it could top a billion dollars. More than 14,000 homes and businesses remained without power or water.

President Obama is scheduled to tour the city Sunday. He has already promised generous federal assistance.

“It is just utter devastation anywhere you look,” said assistant Mayor Melodee Colbert-Kean. “The city is in a state of chaos.”

Meanwhile, the National Weather Service upgraded the fury of the tornado from EF-4 (190 to 198 mph winds)to EF-5 (over 200 mph), the top category.

The increased death toll made it the 8th highest killer tornado in U.S. history, surpassing the 1954 Flint, Mich., twister that claimed 116 lives.

Survivors told harrowing stories of riding out the ferocious twister. Many said they hid in basements, closets, laundry rooms and bathrooms.

Sandy Conlee witnessed the destruction at Greenbriar, a nursing home where 11 people died.

“One of the little old men was standing dazed in the middle of the street when we came out of the home,” said Conlee. “He had blood all over his head. He was in shock.”

Rebecca Wilkinson stood amid the debris that was once the Hampshire Terrace apartment complex. She said she and her young daughter were lucky to be alive.

“I got a call from my mother, and she said to take cover, so I grabbed a blanket and headed to the bathroom,” she said. “By the time I shut the door, it hit.”

Wilkinson clutched her daughter as the apartment collapsed around her.

“If it wasn’t for my toilet and sink, we would have been crushed,” she said. “It was the only thing that held the wall up off of us.”

Rescuers found Wilkinson and her daughter beneath the rubble.

“I handed my daughter out through a hole, and then an elderly gentleman came and pulled me out,” she said.

Wilkinson said she heard shouts and cries of her neighbors as they struggled to free themselves.

“All I could hear were screams,” she said. “If they were there, they’re not now.”

Kevin Fortenbaugh, who lives on Joplin’s north side, was in his pickup truck en route to visit his mother when he noticed the sky suddenly turn black.

He sped ahead to a nearby Wal-Mart, parked the pickup, grabbed his camera and sprinted into the store’s dairy case just as the roof ripped off.

“By the grace of God you get through it,” said Fortenbaugh.

Lifelong Joplin resident Kelly Wells, 45, recalled her story of survival and wondered about her future. Her home was completely destroyed.

“I have nothing,” she said. “It’s all gone.”

Treated for hand, head and rib injuries at a local hospital, she reflected on a service early Sunday morning at the First Christian Church and the sermon about a new beginning.

“Now, I’m like, ‘When’s my new beginning going to start, and what’s it going to be like?’” she asked.