Mexican authorities plan to seal a secret tunnel discovered on January 10, connecting Ciudad Juarez to El Paso, Texas.

The 1,000-foot-long tunnel, hidden within a storm sewer system, featured lighting, ventilation, and reinforced walls, making it suitable for smuggling people or contraband.

Officials believe its construction took one to two years, and an investigation is underway to determine potential complicity by authorities.

Clues about the tunnel were reportedly shared by traffickers on social media, CBS News has reported.

Meanwhile, security on both sides of the U.S.-Mexico border has increased ahead of Donald Trump’s inauguration, with Chihuahua authorities responding to a fire at a migrant camp resisting deportation efforts.

Written by B.C. Begley