The bodies, all male, were found yesterday scattered around 14 shot-up pickup trucks and sport utility vehicles, two of which had bulletproofing.
Television images of the scene near the town of Ruiz showed what appeared to have been a convoy of cartel vehicles that was ambushed or engaged by another column of gunmen on a stretch of rural highway. Military-style boots, bulletproof vests, hand grenades and thousands of rounds of ammunition were found at the scene.
Federal and state officials gave conflicting reports on the incident.
Nayarit state police said officers responding to reports of a kidnapping found four wounded men at the scene of the shootout. One injured person died later, and three remain at the hospital, Nayarit officials said.
The army said two suspects wounded in the battle were found at the scene. It was unclear if the two reported by the army were included in, or additional to, the state figure.
The army said in a statement that around the same time, soldiers engaged in a shootout with armed suspects in a town about 60 kilometres north of Ruiz. Two suspects - a man and a woman - were killed in that confrontation. The military statement did not say whether the two shootouts were related.
Nayarit's attorney general Oscar Herrera told a radio station that preliminary reports indicated the two gangs involved in the fierce highway battle were the Sinaloa and the Zetas drug cartels. He said one of the two cartels kidnapped a man of the rival gang, which resulted in a car chase and subsequent gunfight.
Nayarit and the nearby states of Michoacan and Zacatecas have become battlegrounds for drug cartels fighting for control of the area.
The Sinaloa cartel, Mexico's most powerful, has long been active in Nayarit, which borders its home base in Sinaloa state, but the gang has recently been challenged by the Zetas and by remnants of the Beltran Leyva cartel.
In Michoacan, officials said more than 700 people fled their villages amid fighting between rival drug traffickers, which appeared to be unrelated to the Nayarit conflict.
Michoacan state Civil Defence Director Carlos Mandujano said the villagers were given refuge at five shelters.
It is at least the second time a large number of rural residents have been displaced by drug violence in Mexico. In November, about 400 people in the northern border town of Ciudad Mier took refuge in the neighbouring city of Ciudad Aleman following cartel gunbattles. That shelter has since been closed and most have returned to their homes.
