Six gunmen were killed in a clash with army soldiers outside the northeastern Mexican border city of Matamoros, authorities said.

The Tamaulipas Coordination Group, which is made up of state and federal security forces, reported the number killed in the clash in a statement Friday, saying it took place shortly after midday Thursday in an area known as "Brecha 10" between the municipalities of Valle Hermoso and Matamoros.

Army soldiers were responding to a tip about the presence of several suspicious vehicles in the area, the group said.

After coming under attack by the gunmen, they repelled the aggression and killed "six of the assailants, while the others managed to flee."

The soldiers confiscated 11 rifles, including a Barrett .50 caliber long-range assault rifle, a grenade launcher, hand grenades, ammunition, tactical gear and four SUVs at the scene.

The Gulf, Los Zetas and Sinaloa drug cartels have been fighting for control of Tamaulipas state, where Matamoros is located, and smuggling routes into the United States for years.

Matamoros is located across the border from Brownsville, Texas.