Gunmen on Tuesday shot dead seven taxi drivers on the outskirts of the industrial hub of Monterrey, which has become one of Mexico's most violent cities during a turf war between rival drug cartels.
The taxi drivers were killed as they waited at two depots next to their Volkswagen Beetles in Guadalupe, 3.7 miles from Monterrey's center.
Police officers at the scene said they did not immediately know the motive for the attack, which bore the signs of a gangland killing.
Gangsters in Mexico have targeted some taxi drivers over extortion payments, while other taxi drivers have been alleged to work as spies for drug cartels.
Monterrey, which is home to several of Mexico's biggest companies, has seen a surge in murders this year. Nuevo Leon state, which includes Monterrey, registered a total of 516 homicides in the first quarter of this year, a rise of 31 percent compared to the same period in 2011, according to the governor's office.
In total, more than 50,000 people have been killed since President Felipe Calderon took office in 2006 and began an offensive against drug cartels.
More from msnbc.com and NBC News:
- Syria shells Hama on cease-fire deadline day
- N.Koreans 'unconvincing' answers to satellite questions
- Amid Iran tensions, neighbor becomes den of spies
- Tunnel linked to looming North Korea nuclear test? South Korea thinks so
- Leftist rebels kidnap natural gas workers in Peru
Follow us on Twitter: @msnbc_worldCopyright 2013 Thomson Reuters. Click for restrictions.