SAN ANTONIO – 10:15 a.m. Update:Another crash involving an 18-wheeler has shut down the westbound lanes of Loop 1604, just before Stone Oak, according to San Antonio police. The crash happened Saturday morning at 1200 N Loop 1604. Original:Part of Loop 1604 is blocked after an 18-wheeler lost control while traveling eastbound and crashed into a retaining wall, according to San Antonio police. The crash happened at 5:24 a.m., Saturday, on Loop 1604 just before the NW Military exit. Police said the wet road caused the 18-wheeler to jackknife and crash into the retaining wall.