Mexican law enforcement agencies said Monday they seized over 20 tons of methamphetamine at the biggest drug lab found during the current administration.

The Mexican navy said Monday that the lab was located in Quiriego, a township in a remote part of the northern border state of Sonora.

It said the 91,000 pounds of meth found there was equivalent to about half of the 162,000 pounds of the drug Mexico has seized all year so far. Another 28,000 pounds of meth chemicals were found, the navy said.

Previously, most big meth labs had been found in Sinaloa, but it appears the increasingly violent state of Sonora has become a center of production, and not just a smuggling route.