Two U.S. citizens and 12 Mexican nationals were arrested Monday and federal authorities seized 1,100 pounds of marijuana east of Nogales.

The marijuana is worth an estimated $600,000, according to a U.S. Customs and Border Protection news release.

On June 26, Border Patrol agents patrolling Arizona Highway 82 said they spotted a suspicious Ford van heading east from Nogales. The van stopped at an intersection and the driver and a passenger climbed out of the van and ran, said authorities.

Both men, who were U.S. citizens, were taken into custody a short distance away. Agents looked inside the van and found dozens of large marijuana bundles, said officials.

In the meantime, two Air and Marine Operations helicopters searched the area for possible accomplices. The air crew spotted a group of 12 men walking south away from the highway, authorities said.

Agents descended down a rope from the helicopter and pursued the men, while another air crew guided another group of agents on all-terrain vehicles. The two teams closed in on the men, and took the dozen into custody, said officials.

The two U.S. citizens face federal drug smuggling charges. Four other men face immigration violations, and eight men were processed for expedited removal from the United States, authorities said.