The bodies were discovered near a shopping centre in Boca del Rio, along Mexico's Gulf coast, state prosecutor Reynaldo Escobar told the Milenio television station, horrifying passers-by who forwarded pictures of the scene over social media websites. Some show stopped drivers leaning out of their cars.
"These were people involved in organised crime," Escobar said of the victims. All seven identified hours after the discovery had criminal records, he added. Local media reported some of the bodies, of both men and women, were found with their hands bound and showing signs of torture.
Violence between rival drug cartels has been heating up in the coffee- and sugar-growing state of Veracruz and daily newspaper Milenio said the dead were members of the feared Zetas crime gang, the target of several recent official round-ups in the region.
About 42,000 people have been killed since President Felipe Calderon launched a campaign against drug cartels at the beginning of his term in late 2006.
Most of that violence has been focused on the northern border with the United States, but has started encroaching on other parts of the country as some gangs fracture and old alliances dissolve.
Violent incidents in Veracruz had been rare until recently, but a group of armed men hurled a grenade into a popular area of the city in August, killing one person. This week, 32 prisoners escaped from jails in Veracruz state, but Escobar said there was no sign any of the escapees were among the dead.
"We have never seen a situation like this before," he said.
The Gulf of Mexico port is used to ship goods to Europe, making it a coveted spot for the crime gangs to control as the groups expand their global reach, said independent Mexican security expert Alberto Islas.
"Veracruz is an important strategic port. That has always been true for trade and commerce, but it's now also true for drug exports," Islas said.
Europe is becoming a more attractive market for Mexican drug cartels, particularly due to cocaine consumption, said Islas.
While the Zetas and Gulf cartels have had a strong foothold in Veracruz, other gangs like the Beltran Leyva and Sinaloa cartel are also moving in, Islas said.
The Zetas are a paramilitary-style group founded by deserters from Mexico's army special forces which split off from its former employer, the Gulf cartel.
They were blamed for a recent attack on a Monterrey casino that killed more than 50 people, many of them women, and for the massacre of 72 migrants last year.
The Zetas and their former bosses are now fighting a battle for lucrative drug-smuggling routes to the United States in a rivalry which has engulfed the prosperous business city of Monterrey and the state of Tamaulipas in northern Mexico and could now be spreading south.
