© CBS 5NOGALES, AZ (AP/CBS5) -
Federal authorities have unearthed an unfinished border tunnel near Nogales, making it the fourth tunnel found in a week.
U.S. Immigration and Customs Enforcement spokeswoman Amber Cargile said the Homeland Security Investigations-led Nogales Tunnel Task Force found the incomplete tunnel on Friday and it didn't appear to be in use. Authorities believe the tunnel's aim was to smuggle drugs into the U.S.
Cargile said the tunnel entrance which was located on a storm drain wall on the Mexican side of the border was concealed by rocks. It was four feet in length, five feet wide and three feet tall, running parallel to a storm drain pipe.
Earlier this week, federal officials found three sophisticated drug smuggling tunnels equipped with lighting and ventilation. Two were found in the San Diego-Tijuana area, and another was found in a vacant strip mall storefront in the southwestern Arizona city of San Luis.
Cargile said the investigation into the Nogales tunnel was ongoing. No arrests have been made.
Copyright 2012 Associated Press. All rights reserved. CBS 5 (Meredith Corporation) contributed to this report.
