A man carrying $10 million in U.S. currency was arrested Friday at Tijuana’s A.L. Rodriguez International Airport, authorities said.

The man was taken into custody after he tried to pick up the money — bills of different denominations that had been stuffed into 31 white plastic sacks, according to a statement from Mexico’s Federal Police.

He was unable to show documentation proving the shipment’s legal origin, police said.

Large cash seizures are often the proceeds of illicit drug sales, and help finance the activities of criminal groups that smuggle drugs across the border.