Suspected drug cartel gunmen opened fire on a hotel being used as a police barracks then attacked it with a car bomb Thursday, wounding eight officers less than 4 miles (6.5 kilometers) from the U.S. border, Mexican officials said.

A Tamaulipas state official said authorities believed the Zetas cartel, one of Mexico's two most powerful criminal organizations, carried out the attack on the Hotel Santa Cecilia in Nuevo Laredo, a city across the border from Laredo, Texas.

The Zetas, founded by Mexican special forces defectors, have carried out a number of sophisticated attacks, but Thursday's assault appeared to be one of the most elaborate. It also appeared to be the first attack directed against Tamaulipas' new state police force, which took over a year ago from a municipal police force in Nuevo Laredo that was accused of ineffectiveness and corruption.

The newly commissioned officers, who hail from around the state, were staying in the hotel until permanent barracks were built. Mexican police frequently requisition hotels in the absence of official barracks, or when threats make it unsafe for them to live at home.

The head of state police and Tamaulipas' attorney general said three of the wounded officers had third-degree burns, while the rest had minor injuries.

The attack on the hotel took place around 7:15 a.m. on one of the main streets in Nuevo Laredo, less than four hours after unknown gunmen hurled gasoline bombss at the Maranho, one of the city's most popular nightclubs. The club, which was closed at the time, was badly damaged by fire but there were no injuries, authorities said.

Minutes after the hotel attack, gunmen opened fire on the Nuevo Laredo Institute of Technology, a science-focused university.

Nuevo Laredo is a stronghold of the Zetas. It has been the scene of vicious turf battles between the gang and its former ally, the Gulf cartel, which is now allied with the Zetas' biggest rival, the Sinaloa cartel led by Joaquin "El Chapo" Guzman.

The border city has seen a series of gruesome mass killings in recent week. Fourteen bodies were found in a van in downtown Nuevo Laredo on April 17, and 23 people found hanged or decapitated in the border city on May 4.

Thursday's attack came less than a week after a high-ranking member of the Zetas was arrested and accused of orchestrating the dumping of 49 mutilated bodies in a northern Mexico town square in order to create terror and confusion as part of a battle with the Gulf and Sinaloa cartels.