A gun battle between Mexican soldiers and suspected drug cartel members left 22 dead at ranch near the US border, officials said.
All the dead were suspected gang members, the defence department said in a statement. One soldier was injured.
The military said the drug suspects opened fire on soldiers conducting reconnaissance patrols at a ranch on the outskirts of Ciudad Mier, a northeastern town about 18 miles south of the border with Texas.
Soldiers seized 55 grenades, 18 rifles, four handguns guns, 99 ammunition clips, 1,540 rounds of ammunition and vehicles at the ranch.
They also found military style uniforms, which are frequently used by drug gangs staging attacks.
The fighting erupted hours before celebrations started across Mexico for the bicentennial anniversary of its independence from Spain.
It did not disrupt festivities in the main cities in north-eastern Mexico, where violence has reached war-like proportions this year amid a split between the Gulf cartel and its former gang of henchmen, the Zetas.
In the border city of Ciudad Juarez, gunmen ambushed two newspaper photographers in their car yesterday, killing one and wounding the other.
Mexican journalists are increasingly under siege from cartels seeking to control the flow of information.
Across Mexico, drug-gang violence has claimed an unprecedented 28,000 lives since December 2006, when President Felipe Calderon deployed thousands of troops and federal police to fight the cartels in their strongholds along the US border and in Pacific coast states.