Emergency crews' search in the ruins left by the gigantic tornado that killed two dozen people in Oklahoma on Monday is almost over, say officials.
Fire chief Gary Bird said he was "98% sure" there were no more survivors or bodies to recover from the rubble.
The storm, which also killed nine children, has meanwhile been upgraded to the most powerful level of twister.
Packing winds of at least 200mph (320km/h), the tornado razed a swathe of the Oklahoma City suburb of Moore.
Oklahoma Governor Mary Fallin said the death toll may rise above 24 as some bodies could have been taken directly to funeral homes.
The body count was revised down from 51 after the state medical examiner said some victims may have been counted twice in the confusion.
According to the local fire chief, no survivors or bodies have been found since Monday night.
He said their goal was to conduct three searches of each location just to be sure. The work is expected to be finished by nightfall, although heavy rain has hampered their efforts.
Emergency crews have had trouble navigating the devastated neighbourhoods because there were no street signs remaining. Some used mobile phones and GPS to navigate.
The National Weather Service (NWS) has upgraded the tornado to EF-5, the most powerful type on the Fujita scale. It uses the word "incredible'' to describe the force of such a storm.
The NWS said the twister's path was 17 miles long and 1.3 miles wide.
For about 45 minutes on Monday afternoon, the storm battered the suburb of about 55,000 people.
Emergency workers pulled more than 100 survivors from the rubble of homes, schools and a hospital, while 237 people were known to have been injured.
Seven of the nine children killed in the tornado died at Plaza Towers Elementary, where the storm ripped off the roof and knocked down walls as students and teachers cowered in hallways and bathrooms.
Officials said they were still trying to account for a handful of children not found at the schools who may have gone home early with their parents.
That primary school and one other hit by the storm, Briarwood Elementary, did not have safe-rooms that protect against tornadoes, said Albert Ashwood, of the Oklahoma Department of Emergency Management.
More than 100 schools in Oklahoma had been provided with state-funded safe rooms, he said, but not those two.
Residents were given 16 minutes' warning before the tornado touched down - officials said such advisories were usually issued eight to 10 minutes ahead of a twister.
Oklahoma's insurance commissioner told Reuters news agency the cost of the storm would exceed that of the 2011 tornado in Joplin, Missouri, that killed 158 people. He said the Joplin twister caused $3bn (£2bn) in damage.
US President Barack Obama has declared a major disaster in Oklahoma and ordered federal authorities to join in the search efforts.
"The people of Moore should know that their country will remain on the ground there for them, beside them as long as it takes for their homes and schools to rebuild," he said from the White House.
Heavy-lifting equipment was deployed under bright floodlights as the operation continued overnight and throughout Tuesday.
Rescuers braved the danger of electrocution and fire from downed power lines, as well as ruptured natural gas lines.
More than 200 Oklahoma National Guardsmen together with personnel from other states were called in to help the search-and-rescue effort.
The storm left a tangle of ruined buildings, piles of broken wood, overturned and crushed cars.
Many houses in the area are built on hard ground without basements, so many residents had struggled to find shelter.
Oklahoma City lies inside the so-called Tornado Alley stretching from South Dakota to central Texas, an area particularly vulnerable to storms.
On Sunday, another tornado killed two people near Shawnee, Oklahoma.
The city of Moore was hit by a severe tornado in May 1999, which had the highest winds ever recorded on Earth, over 310mph.