-- U.S. Customs and Border Patrol officers made the biggest marijuana bust at an El Paso port of entry in years.

CBP officers actually made two large finds at the Bridge of the Americas Thursday.

Both involved false compartments in tractor-trailers and they happened about 20-minutes apart.

In the first incident, a canine detected 430 lbs. of marijuana in the rear of a trailer.

In the second, officers noticed a difference in another trailer's interior and exterior length.

They discovered 4,700 lbs. of marijuana by drilling into the wall.

"A concern there is that it was marijuana in this case, but certainly there's enough space there for several people, potential tools of mass destruction," said CBP spokesman Roger Maier.

CBP officers credit layered enforcement for the discovery, starting first with officer expertise, and then using tools and canines to lead to seizures.

This week alone, 12,000 lbs. of marijuana have been confiscated. At this time last year, that number was only at 2,500 lbs.