The northbound lanes of Interstate 37 were shut down on the Southeast Side Wednesday after a major accident involving two 18 wheelers and up to 20 vehicles, according to authorities. The crash occurred shortly before 8 a.m. Wednesday near Old Corpus Christi Road on I-37, where at least two 18-wheelers crashed due to the heavy fog in the area in the northbound lanes, said San Antonio Police Department Sgt. George Antu. All lanes of I-37 finally opened at about 11:40 a.m., according to SAPD. The multi-vehicle pileup was the result of four to five different crashes on I-37, according to Texas Department of Transportation spokesman Josh Donat.