Hundreds of thousands of people are without power in Texas as severe thunderstorms batter the north-east region of the US state.
Officials said the latest round of storms will bring hurricane-force wind gusts of up to 77mph (123km/h) and golf ball-sized hail.
Tuesday’s extreme weather follows several weekend storms that killed at least 24 people across five states, including Texas.
Sweltering heat is also forecast for southern Texas on Tuesday, where temperatures could feel up to 115F (46C).
Some north Texans awoke on Tuesday to the sound of tornado sirens, after the National Weather Service (NWS) issued warnings in Dallas and surrounding areas due to the heavy thunderstorms.
There were reports of flooding of residential streets, downed trees and powerlines throughout the city, according to local newspaper the Dallas Morning News.
More than half of the 780,000 power cuts reported on Tuesday were in Dallas County, where schools have cancelled or delayed classes and activities for the day tue to the severe weather.
Hundreds of flights out of Dallas were also delayed or cancelled as of late Tuesday morning because of the storms.
The Dallas Zoo said on Twitter/X that it took a “significant hit” and would also close on Tuesday as it assesses the damage.
Nearly two dozen counties in Texas remain under a severe thunderstorm watch into Tuesday afternoon
The NWS said additional storms with “large hail and damaging wind” could continue in the region into the evening, and that “a tornado or two cannot be ruled out.”
It also warned about the potential of flash flooding in northern and central Texas, as well as parts of southern Oklahoma.
Texas suffered a devastating weekend of storms that killed at least seven people in the state and injured more than 100.
Of those killed were three children - a two-year-old and a five-year-old who belonged to the same family, and another nine-year-old.
Officials estimate that more than 200 homes or structures were destroyed and another 120 were damaged. The area with the heaviest damage was Cooke County, where a tornado with winds up to 135 mph (217 kph) had struck.
Footage from the area showed a filling station and rest stop almost completely destroyed, with twisted metal littered over damaged vehicles.
Other storm-related deaths over the weekend were reported in Arkansas, Oklahoma, Kentucky and Alabama.
As northern Texas is battered with storms, the southern part of the state will be hit with searing temperatures - part of a heat wave that has hung over the region in recent days.
The NWS said high temperatures are also expected to remain above average or near record-high throughout central and southern Florida over the next few days.
The latest rounds of severe US weather follow another powerful tornado which tore through a rural Iowa town and killed four people earlier in May.
Government forecasters have also described this summer as a possibly "extraordinary" 2024 Atlantic hurricane season, beginning next month.