October tornadoes are not common, and cities are rarely hit, according to Harold Brooks of the National Severe Storms Laboratory in Norman, Oklahoma.
NWS meteorologist Jennifer Dunn said there may have been two or more tornadoes in north Texas but the extent would not be known until later when crews have surveyed the damage.
Dallas Fire-Rescue said one of its stations sustained significant damage during the storms overnight, posting photos on Twitter that show a collapsed roof and debris.
The storm disrupted flights in north Texas and north-west Arkansas.
According to Flightaware.com, 63 flights were delayed and 18 cancelled at Dallas Love Field on Monday, while 78 were cancelled at Dallas-Fort Worth International Airport and more than 200 were delayed.