One of Reynosa's busiest districts came to a standstill following a chase that brought troops through the city's center.
Reynosa residents turned to Twitter to reported what happened.
Witnesses reported everything started with a tire spikes being thrown outside a Chedraui supermarket on the city's southside around 2 p.m. Wednesday.
Minutes later, troops were seen in the "peatonal" or "pedestrian precinct" market of downtown Reynosa.
Witnesses reported that the area was packed with afternoon shoppers but emptied within minutes.
Mexican army officials did not have any information at this time but witnesses reported hearing gunfire.
The witnesses reported casualties, wounded and arrests and that soldiers returned to the area again at 4 p.m. but no official information has been released at this time.
Action 4 News will provide more information as it becomes available.