Seven people died in a nearly 15-hour battle between gunmen and soldiers in Mexico, defence department said on Monday.
The clash began on Sunday night when troops tried to search a house in Panuco, a town in the northern part of the Gulf coast state of Veracruz, the department said in a statement.
The troops, who went to the house after an anonymous tip about the presence of armed men, "were attacked with gunshots ... and grenades," according to the official statement.
After hours of intermittent combat, the soldiers "neutralised the aggressors and entered the building" to find six gunmen dead inside. One soldier was killed and five others wounded, while six gunmen were arrested.
Besides the six gunmen and one soldier, a civilian was found dead at the scene, Veracruz Attorney General Salvador Mikel Rivera said.
The shootout in Veracruz began just hours after a mayor was slain in the neighbouring Gulf coast state of Tamaulipas.
Marco Antonio Leal Garcia, mayor of the city of Hidalgo, was killed on Sunday while driving with his daughter, the Tamaulipas attorney general's office said.
Tamaulipas, which borders Texas in the US, has been suffering from a wave of violence unleashed by drug traffickers battling for control of smuggling routes into the US.
About 28,000 people have died in drug-related violence since President Felipe Calderon declared war on Mexico's cartels shortly after taking office in December 2006.