SAN ANTONIO -- A collision involving two vehicles and three 18-wheelers has shut down the northbound lanes of Interstate 35 in Frio County south of San Antonio.

Two people were injured in the collision and have been airlifted to University Hospital, according to law enforcement officials. Their conditions are not known.

The collision occurred about 2:45 p.m. near mile marker 115 and has shut down the northbound lanes of I-35. Law enforcement officials told KSAT 12 News they expected the interstate to be cleared by 4:45 p.m., but views from Sky 12 at 4:42 p.m. show traffic still being diverted just before the overpass.