I-45 southbound main lanes are closed at Hwy 30 in Huntsville, due to a crash that occurred less than 30 minutes ago, when an 18-wheeler slammed into another 18-wheeler that was stopped dealing with a flat tire. The second big rig then did major damage to a passenger vehicle. The Southbound lanes of I-45 at that intersection will be closed for hours as the crash(es) are documented, investigated, and eventually cleared (which may or may not require special cleanup).