(CNN) —  

Two men tried to hide methamphetamine worth more than $1 million in the gas tanks of two vehicles, but were thwarted by drug-sniffing dogs over the weekend, the U.S. Border Patrol said Monday.

The two men were stopped hours apart at two checkpoints as they drove north through California. One was a 23-year-old American who was asked Saturday morning to pull to the side for further inspection at a U.S. Customs and Border Protection checkpoint about 25 miles east of San Diego.

A K-9 zeroed in on the gas tank of the 1998 Camry the man was driving. Inside agents say they found 72 pounds of methamphetamine in 30 packets. The methamphetamine has a street value of $720,000, authorities said.

At another Border Patrol checkpoint an hour north of San Diego, agents discovered 75 pounds of methamphetamine worth $750,000 in the gas tank of a Chevy Silverado. CNN affiliate KSWB reported the driver is a 39-year-old Mexican citizen.

Authorities didn’t release the identity of either man and didn’t say the two cases were connected. They were turned over to the Drug Enforcement Administration.