EL PASO, Texas (AP) — The U.S. Border Patrol says a road construction crew has uncovered an abandoned tunnel in Texas, just north of the border with Mexico.

Agent Oscar Cervantes says the tunnel was discovered Thursday near downtown El Paso.

The Border Patrol said in a statement that the Texas Department of Transportation reached out after a cave-in during construction of a road. The mishap led to the discovery of the tunnel that originates north of the international border.

Authorities do not know the purpose of the tunnel or where it goes.

Border Patrol confined-space resource teams are examining the area to determine the extent of the tunnel, apparently reinforced with wooden beams.

Cervantes declined to release further details Friday, citing the ongoing investigation.