Updated

AJO, Ariz. -- Border agents say they seized 4,000 pounds of marijuana worth more than $3.1 million in two separate incidents in southern Arizona.

Border Patrol spokesman Eric Cantu said Wednesday that agents from Ajo's all-terrain vehicle unit were tracking footprints of suspected illegal immigrants on Monday when they found more than 2,200 pounds of abandoned pot that were bundled and fashioned into backpacks to carry easily.

In the second incident, the ATV unit found an abandoned vehicle while patrolling west of Lukeville. It had numerous bundles of pot weighing about 1,750 pounds.

All the pot was seized.

The Border Patrol's Tucson sector seized more than 940,000 pounds of marijuana worth more than $752 million from Oct. 1, 2009 through Aug. 31 of this year.