Updated

As rescuers scour the rubble of tornado-ravaged Moore, Okla., desperately searching for trapped survivors, recent history shows there is reason for hope.

Word that the death toll had been vastly overstated, prompting a rare downward revision early Tuesday, provided hope for survivors. Local responders, augmented by three FEMA Urban Search and Rescue teams, were going from home to devastated home, listening for anguished cries, watching for signs of life and gingerly dismantling piles of debris,

“As of 10 o’clock this morning, we had 151 people on the ground in Oklahoma, with more scheduled to arrive today,” a FEMA official told FoxNews.com.

Late Monday and early Tuesday, families gathered at St. Andrews United Methodist Church, waiting and hoping for word that loved ones have been found alive. On Monday night, the Oklahoma City medical examiner’s office said at least 51 people had died and 40 more bodies were expected, but on Tuesday, the office said it could only confirm 24 deaths.

Cutting the death toll by more than half buoyed hopes for survivors, but the process of locating and rescuing them is slow. At Plaza Towers Elementary School, which took a direct hit from the twister, rescue workers found several children and were still working their way through the destruction.

“We are still definitely in search-and-rescue mode,” said town spokesman Jayme Shelton.

Recent natural disasters show the rescue process could go on for days, if not weeks:

May 10, 2013 – Rescue workers in Savar, Bangladesh, freed a woman buried for 17 days inside a prayer room in the wreckage of a collapsed garment factory building. The death toll from the disaster raced past 1,000, making it one of the worst industrial tragedies in history.

Oct. 26, 2011 – Two university professors and a student were rescued from building ruins in Turkey three days after a magnitude 7.2 earthquake hit the area, killing at least 461 people and injuring more than 1,350.

March 19, 2011 – An 80-year-old woman and her 16-year-old grandson survived freezing temperatures and heavy snow, eating yogurt from their fridge, and were pulled alive from rubble in Ishinomaki City, Japan, nine days after an earthquake and tsunami devastated the area, killing an estimated 15,000 people.

Jan. 28, 2010 – French rescuers pulled a 16-year-old Haitian girl out of the rubble of a collapsed college in Haiti, more than two weeks after a magnitude 7.2 earthquake devastated the island nation’s capital, killing an estimated 170,00 people.

May 25, 2008 – Eleven days after an earthquake killed more than 60,000 people in Sichuan Province, China, an 80-year-old man, paralyzed prior to the quake, was found alive underneath one of his home’s support beams.