Explosive Found on Texas Road Near Mexico Border

BROWNSVILLE, Texas --

Federal agents are investigating an improvised explosive device found on a Texas highway near the Mexico border.

Brownsville Police spokesman Eddie Garcia says a passing motorist alerted authorities about 5 p.m. Sunday to a grenade modified and left on an overpass along southbound U.S. 77. A bomb squad shut down traffic for three hours to disarm it.

Garcia said Tuesday the device had no trigger, was poorly built and "would have caused minimal damage." Still, the FBI and U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives were contacted as a matter of protocol.

No arrests have been made and authorities have yet to determine why the device was on the highway.

It was found north of downtown Brownsville, which borders Matamoros, Mexico.