REYNOSA, Tamaulipas — Eight innocent bystanders and motorists were injured in a cartel skirmish as rival gunmen squared off near a shopping center in one of this border city’s main avenues. The fighting led to at least one shooter dying.

The incident took place outside a popular shopping center called H100 along Boulevard Hidalgo and quickly spread to two other neighborhoods as rival Gulf Cartel gunmen exchanged shots. Mexican military personnel and Tamaulipas state police rushed to the area, but were not able to stem the violence. Reynosa is immediately south of the U.S. cities of McAllen, Hidalgo, Pharr, and…