Authorities are searching for about a dozen illegal immigrants following a bailout just north of San Manuel.
It all happened on U.S. Highway 281 about 10 miles north of FM 1017 just after 7 p.m. Thursday.
Investigators said it all started with a traffic stop by Hidalgo County Precinct 4 deputy constable.
One person was detained but at least a dozen immigrants bailed out from the vehicle.
Deputy constables, state troopers and Border Patrol agents have all been called to scene.