There are multiple tornadoes on the ground in the Dallas area right now, and one has already caused significant damage after ripping through an entire tractor trailer parking lot. The video above, from CNN's broadcast, clearly shows a number of 18-wheelers being picked up hundreds of feet in the air.
The AP reports that there is "a funnel cloud on the ground near Interstate 35 south of Dallas"; other reports place a tornado near Lancaster and moving north. There are also plenty of terrifying images on Twitter. We'll update as needed, and you can watch live news reports here and here. Gizmodo is also providing regular updates.