Another big bust was made by the Starr County High Intensity Drug Trafficking Area Task Force on Thursday.
According to a release, Broder Patrol agents working the area of La Casita encountered several subjects carrying bundles of marijuana on their back at the river banks by the Los Puertos area.
Authorities said the mules fled back to Mexico and were not apprehended.
However, agents seized nine bundles of marijuana with a combined weight of 517 pounds.
The case remains under investigation.