MOORE, Okla. — A massive tornado flattened homes and destroyed at least two schools packed with children near Oklahoma City on Monday, sending rescuers and residents dashing to dig out buried survivors.
Amy Elliott, the spokeswoman for the Oklahoma City medical examiner, said at least 91 people had died, including 20 children, and officials said the death toll probably would climb.
As the injured began flooding into hospitals, the authorities said many people remained trapped. Rescue workers struggled through debris-clogged streets to reach the devastated suburb of Moore, where much of the damage occurred.
Hospitals reported at least 145 people injured, 70 of them children.
Plaza Towers Elementary School in Moore was reduced to a pile of twisted metal and toppled walls. Workers tore through rubble amid reports that dozens of students were trapped.
Children from the school were among the dead, but several students were pulled alive from the rubble. Rescue workers passed the survivors down a human chain to the triage center in the parking lot.
James Rushing, who lives across the street from the school, heard reports of the approaching twister and ran to the school, where his 5-year-old foster son, Aiden, attends classes. Rushing believed he would be safer there.
‘‘About two minutes after I got there, the school started coming apart,’’ he said.
A man with a megaphone called out the names of surviving children. Parents waited nearby.
At Briarwood Elementary School in Oklahoma City, on the border with Moore, cars were thrown through the facade and the roof was torn off.
“Numerous neighborhoods were completely leveled,’’ Sergeant Gary Knight of the Oklahoma City Police Department, said by telephone. ‘‘Neighborhoods just wiped clean.’’
He said debris and damage to roadways, along with heavy traffic, were hindering emergency responders.
A spokeswoman for the mayor’s office in Moore said emergency workers were struggling to assess the damage.‘‘Please send us your prayers,’’ she said.
Brooke Cayot, a spokeswoman for Integris Southwest Medical Center in Oklahoma City, said 58 patients had come in by about 9 p.m. Another 85 were being treated at the Oklahoma University Medical Center in Oklahoma City.
‘'They've been coming in minute by minute,’’ Cayot said.
Oklahoma Governor Mary Fallin deployed 80 National Guard members to assist with rescue operations and activated extra highway patrol officers.
Fallin also spoke with President Obama, who gave Fallin a direct line to his office. He later declared the area a major disaster and ordered federal aid to supplement state and local recovery efforts.
Many land lines to stricken areas were down, and cellphone networks were congested. The storm was so massive that it will take time to establish communications between rescuers and state officials, the governor said.
Keli Pirtle, a spokeswoman for the National Weather Service in Norman, Okla., said the tornado touched down at 2:56 p.m., 16 minutes after the first warning went out, and traveled for 20 miles. It was on the ground for 40 minutes, she said. It struck the town of Newcastle and traveled about 10 miles to Moore, a suburb of 41,000 people about 10 miles south of Oklahoma City.
Pirtle said preliminary data suggested that it was a Category 4 tornado on the Enhanced Fujita scale, which measures tornado strength on a scale of 0 to 5. A definitive assessment will not be available until Tuesday, she said.
Moore was the scene of another huge tornado in May 1999 in which winds reached record speeds of 302 miles per hour.
Destruction Monday spread over a vast area, with blocks upon blocks of homes and businesses destroyed. Residents, some partly clothed, picked through rubble. Several structures were on fire, and cars had been flipped over and stacked on top of one another.
Kelcy Trowbridge, her husband, and their three young children piled into their neighbor’s cellar just outside of Moore and huddled together for about five minutes, wrapped under a blanket as the tornado screamed above them.
They emerged to find their home flattened, and the family car upside down a few houses away. Trowbridge’s husband rushed toward what was left of their home and began sifting through the debris, then stopped, and told her to call the police. He had found the body of a little girl, about 2 or 3 years old, Trowbridge said.
''He knew she was already gone,’’ said Trowbridge. ‘‘When the police got there, he just bawled.’’
Russell Schneider, the director of the National Oceanic and Atmospheric Administration’s Storm Prediction Center in Norman, Okla., said the risk of tornadoes throughout the region remained high.
An earlier storm system also spawned several tornadoes across Oklahoma on Sunday. Several deaths were reported.
Some parts of Moore seemingly emerged untouched by Monday’s tornado. Bea Carruth, who lives about 20 blocks from where the storm struck, said her home and others in her neighborhood appeared to be fine.
Carruth had ridden out the tornado as she usually does, at her son’s house nearby, the hail pounding away on the cellar where they'd taken shelter. Tornadoes have long been a part of life in Moore, she said, and a few times a year, in a well-worn ritual, she goes into her son’s cellar when the sirens go off.
In 1999, the last time a storm this size struck, Carruth again was lucky and the home she lived in then was spared. She ended up buying an empty plot of land where a house destroyed by that tornado once stood.
Her house now sits on that plot.
''This is just awful,’’ she said. ‘‘It all just breaks my heart.’’