A man was injured and a woman was arrested after the pair rode on a big rig truck early Thursday morning.
The truck driver was making his way through South Bexar County when he heard someone knocking on the cab of the big rig.
It turns out a man and a woman were hanging off of the truck, trying to get inside.
The man fell off the truck at some point and was taken to the hospital. Meanwhile, deputies took the woman into custody for questioning.
Deputies shut down I-37 near Loop 1604 for several hours while they investigated.