Mexico's navy says six people are dead after a group of suspected criminals sparked a skirmish by opening fire on a Marine helicopter near the U.S. border.

The navy says the incident happened on Sunday in a rural area south of Nuevo Laredo, which is across the border from Laredo, Texas.

In a statement Monday, the navy said the suspects fired on the Blackhawk helicopter, hitting it seven times. The helicopter crew returned fire, killing six suspects. No navy personnel were injured.

The navy said the crew detected a convoy of armed men in an area long dominated by the Zetas cartel.

In a May 1 attack, gunmen in the western state of Jalisco shot down an army helicopter with a rocket launcher, killing 10.