The National Transportation Safety Board announced Sunday that it's sent a team to Alabama to help investigate a fiery multi-vehicle crash that killed 10 people, including nine children.

The big picture: Saturday's crash, south of Montgomery, occurred amid a tropical depression that left 13 people dead in Alabama. It triggered flash floods and tornadoes that razed "dozens of homes" in the Southeast over the weekend, per AP. Parts of the Midwest were also badly hit, including Indiana and Chicago, where a tornado struck late Sunday.

[11:11 PM CDT] Confirmed tornado (via tornado debris signature) near route 53/75th street in Woodridge. If you're in the path of this storm, take cover now! #ilwx

— NWS Chicago (@NWSChicago) June 21, 2021

• There were reports of widespread power outages in Chicago from the storm system overnight. The National Hurricane Center said earlier Sunday that southeast Louisiana, southern Mississippi, southern Alabama and the western Florida panhandle saw rainfall up to 10 inches with isolated 15-inch amounts.
• The National Weather Service issued flash flood watches and tropical storm warnings for much of Georgia and the Carolinas Sunday night.

Zoom in: Butler County Coroner Wayne Garlock told the Washington Post investigators believe a vehicle hydroplaned on "waterlogged roads" at a bridge on Alabama's Interstate 65, causing a "chain reaction."

• Police said seven vehicles caught fire in the ensuing pile-up. Eight children died in a Tallapoosa County Girls Ranch van, operated by the Alabama Sheriffs Association. A man and his baby died in another vehicle during the crash.
• Ranch director Candice Gulley, the van's sole survivor after a bystander pulled her from the flames, was in a serious but stable condition in a hospital, AP reports.

NTSB investigation will focus on vehicle technologies such as forward collision warning systems, CMV fuel tank integrity, motor carrier operations and occupant survivability. NTSB investigators will arrive in the area Sunday evening.

— NTSB_Newsroom (@NTSB_Newsroom) June 20, 2021

What to watch: "Claudette is expected to slowly strengthen over the Carolinas as it approaches the Mid-Atlantic Coast from the west," the NWS said in a statement Sunday.

• "Tropical Storm conditions are expected to develop along the coastal regions of the Carolinas before the storms moves into the Atlantic. Severe storms are possible across the Northeast U.S. Monday."

Editor's note: This article has been updated with new details throughout.