MEXICO CITY - Dark days of violence have returned to Mexico's northeastern state of Tamaulipas, prompting authorities to deploy more soldiers after nearly 80 people died in drug cartel gunfights in one month.
A spate of shootings in broad daylight and high-speed chases through city streets have turned Tamaulipas into a new security challenge for President Enrique Pena Nieto.
On Wednesday authorities announced the arrest of 10 state police officers for alleged links with organised crime. Press reports said they may be tied to the murder of a police chief.
Until now, the western state of Michoacan had been the centre of attention after the federal government deployed thousands of troops to end battles between vigilantes and the cult-like Knights Templar drug cartel.
But a new bout of violence has put the spotlight again on Tamaulipas, a state bordering the United States that has endured some of the worst carnage in Mexico's drug war.
The shootings have broken a rare lull in a state accustomed to battles between the Zetas and Gulf cartels, former allies that turned on each other in recent years.
Many of the 80,000 victims of Mexico's drug war have died along the country's northern states since 2006, due to their prime locations as lucrative drug trafficking routes to the United States.
Officials say the latest spate of violence is the result of crackdowns on gangs and an internal feud within the Gulf cartel following the arrests of top capos.
At least 77 people have been killed since April 5, according to official figures, even as the federal government says killings have fallen nationwide since Pena Nieto took office in December 2012.
Violence linked to arrests
One of the most recent victims was the director of state police investigations, Salvador de Haro Munoz, who was killed late Monday in a clash that also left four suspects dead in the state capital, Ciudad Victoria.
The violence led to the deployment of some 200 marines and federal police officers to the state, said Tamaulipas government spokesman Guillermo Martinez.
The state government says the recent arrival of a military man as the new state security chief, General Arturo Gutierrez, has put pressure on criminal groups.
After taking over in March, "the general began to squeeze and logically this led to clashes because the investigations started to show results," Martinez told Radio Formula on Wednesday.
Governor Egidio Torre Cantu has named another general to oversee security in the port city of Tampico on the Gulf of Mexico coast.
One of the bloodiest episodes took place in Tampico and the neighbouring town of Ciudad Madero last month.
In just three days, between April 5 and 8, a series of gunfights left 28 people dead in the two cities, with bodies dropping in streets, a fuel station and an ice cream shop. Authorities blamed the killings on a gang feud.
Torre Cantu is mulling whether to name more military officers to security posts.
"The possibility of naming eight or 10 more coordinators to divide the state in zones and have more control is being analysed," a state government official told AFP on condition of anonymity.
"It's not a question of militarizing security but finding people with more experience," the official said.
Some analysts say the federal government should send a special envoy to oversee security in the state, like the commissioner deployed to Michoacan earlier this year.
But Torre Cantu, who took office in 2010 after his brother and then-candidate for governor was assassinated during the campaign, has rejected the idea.
Raul Benitez Manaut, security expert at Mexico's National Autonomous University, said Tamaulipas cannot be compared to Michoacan, "where the state government is inoperative and the people are armed."