Police on Wednesday arrested a man who was weaving in and out of traffic on Highway 281 by Nakoma after a detective in an unmarked vehicle saw the erratic driving.
Officers on the scene said the driver hit a few walls on the highway.
A San Antonio police detective in an unmarked vehicle and an off-duty deputy saw the man driving erratically.
The detective also followed him with his hazards on to prevent other drivers from getting in his path.
The driver exited the highway near San Pedro and Rhapsody, where he rear-ended a truck that was stopped at a light.
That's when police took the man into custody and administered a sobriety test.
Police said he facing charges of driving under the influence and possession of narcotics. His identity has not been released.