A man is dead after being struck by a UPS 18-wheeler early Wednesday morning on a Loop 410 access road, and police are investigating whether another vehicle hit him first and drove away.

Officers responded to the scene at around 2:35 a.m. on the eastbound access road near North Vandiver Road, not far from Harry Wurzbach Road.

According to SAPD, a witness told police the man was already on the ground when he was hit by the UPS 18-wheeler.