With the number of Helene's victims reaching at least 100 on Monday, the powerful storm that swept the Southeast and triggered epic rainfall has become one of the deadliest hurricanes to make landfall on the U.S. mainland in the modern era.

Since 1950, only eight hurricanes have claimed more than 100 lives in the contiguous 48 states. Hurricane Harvey, which flooded Houston and the surrounding region in 2017, killed 103.

Deaths have been reported by officials in the Carolinas, Florida, Georgia and Tennessee. Falling trees was the biggest cause of death among they preliminary reports.

Hundreds of people remain missing, and search and rescue operations were underway Monday in Florida, North Carolina and Tennessee, officials said. Trained teams are responding from across the country, said Diana Marty, overseeing search operations in Pinellas County, Florida, where at least nine deaths have been reported as a result of the historic storm surge Helene pushed in along the coast.

Cataclysmic flooding has devastated communities along the Blue Ridge mountains from Georgia into Tennessee. Helene, and a wave of moisture ahead of the hurricane, dumped an overwhelming 10 to 30 inches of rain. forcing raging torrents of water from steep ridges into narrow valleys.

At least 35 people dead in one NC county

North Carolina has been especially hard hit. The confirmed death toll in Buncombe County alone climbed to 35 and was expected to rise, officials said. About 600 missing persons reports remain, although many are expected to be resolved when communications are restored, authorities said.

And the number of victims could grow. In Unicoi, Tennessee, where one death was confirmed Sunday, Myron Hughes, spokesperson for the Unicoi County Emergency Management Agency said: "We do expect this number to change."

Hurricane Katrina, which struck Mississippi and Louisiana in August 2005, remains the most deadly storm since 1950, and the third most deadly dating back to the 1800s.

Maps show devastation:Track Hurricane Helene's 800-mile path of destruction across Southeast

Deadliest hurricanes in the US

The deadliest hurricanes, based on National Hurricane Center information, are listed below by their rank, name, year and number of deaths.

1. Katrina - 2005, 1,392
2. Audrey - 1957, 416
3. Camille - 1969, 256
4. Sandy - 2012, 219
5. Diane - 1955, 184
6. Ian - 2022, 156
7. Agnes - 1972, 122
8. Harvey - 2017, 103
9. Helene (preliminary), 100
10. Hazel - 1954, 95
11. Irma - 2017, 92
12. Ike - 2008, 85
13. Ida - 2021, 87
14. Betsy - 1965, 75
15. Andrew - 1992, 65
16. Rita - 2005, 62
17. Carol - 1954, 60
18. Michael - 2019, 59
19. Ivan - 2001, 57
20. Floyd - 1999, 56
21. Matthew - 2016, 52
22. Florence - 2018, 52
23. Isabel - 2003, 51
24. Donna - 1960, 50

Source: National Hurricane Center reports

Contributing: Areena Arora, Knoxville News Sentinel

Dinah Voyles Pulver covers climate change and the environment for USA TODAY. She's written about hurricanes, tornadoes and violent weather for more than 30 years. Reach her at [email protected] or @dinahvp.