A "bomb cyclone" swept through the central part of the US on Wednesday, leaving heavy snow and rainfall in a region already plagued by flooding.

Colorado, Wyoming, South Dakota, North Dakota, Wyoming, Minnesota, and Wisconsin all saw heavy snowfall, with South Dakota reportedly seeing at least 18 inches in some parts of the state so far. Some areas are expecting as much as 30 inches before the storm system subsides.

The blizzard’s “life-threatening” conditions prompted Colorado Governor Jared Pollis to activate the National Guard. They’ll deploy 24 vehicles in preparation for possible rescues. The state also grounded as many as 300 flights.

State offices in Colorado and South Dakota, where power outages were reported, also closed Wednesday. Officials in both states have urged citizens in affected areas to leave work early.

In Minnesota, as many as 200 crashes have been reported since the storm began on Wednesday. Schools in St Paul and Minneapolis have closed due the weather. Minnesota Governor Tim Walz has also called on the National Guard, particularly to retrieve drivers.

Traffic throughout all states affected has been halted, with major closings across interstate systems.

Bomb cyclone brings floods to US midwest Show all 12 1 /12 Bomb cyclone brings floods to US midwest Bomb cyclone brings floods to US midwest Spencer Dam bursts in Bristow, Nebraska on March 16 Reuters Bomb cyclone brings floods to US midwest Snow drifts on a house in Yoder, Colorado on March 15 AP Bomb cyclone brings floods to US midwest Flooded flats on the Elkhorn River in Nebraska on March 16 Reuters Bomb cyclone brings floods to US midwest A road is flooded after the Pecatonica River burst its banks in Freeport, Illinois on March 18 Getty Bomb cyclone brings floods to US midwest Cars sit in floodwater from the Pecatonica River in Freeport, Illinois on March 18 Getty Bomb cyclone brings floods to US midwest A church is surrounded by floodwater from the Pecatonica River in Freeport, Illinois on March 18 Getty Bomb cyclone brings floods to US midwest A church is surrounded by floodwater from the Pecatonica River in Freeport, Illinois on March 18 Getty Bomb cyclone brings floods to US midwest Cars sit in floodwater from the Pecatonica River in Freeport, Illinois on March 18 Getty Bomb cyclone brings floods to US midwest Flooding in Valley, Nebraska on March 16 Reuters Bomb cyclone brings floods to US midwest A damaged highway in Nebraska on March 16 Reuters Bomb cyclone brings floods to US midwest Abandoned cars on the side of Highway 94 in Yoder, Colorado AP Bomb cyclone brings floods to US midwest A handout picture made available by the National Oceanic and Atmospheric Administration (NOAA) shows winter storm Ulmer becoming a 'bomb cyclone' EPA

Last month, a late-winter bomb cyclone covered the same region with heavy rainfall, resulting in flooding. Some areas of Iowa and South Dakota, the latter of which is was heavily hit by the bomb cyclone, are still flooded. This blizzard threatens the area with still more flooding after the fallen snow, which for now has slowed potential runoff, melts.

"We're calling it historic because of the widespread heavy snow,” Mike Connelly, a weather service meteorologist in Aberdeen, South Dakota, told the Chicago Tribune. “We will set some record.”