Gunmen attacked police in three separate incidents in Mexico. In Acapulco, they barged into two police stations, killing a total of 7 people. Forensics experts roped off the scenes, carrying bodies into a van, but admitted they have much work to do to catch the killers. In the northern city of Culiacan, a police chief was gunned down while on patrol. He is the third police chief murdered in Sinaloa this year and was shot over 100 times. No one has been apprehended in any of the cases. Drug-related violence has surged in both regions in the past year. Mexican gunmen attacked police in three separate incidents on Tuesday (February 6), killing seven people in two Acapulco police stations and killing a police chief in Sinaloa state while on patrol. In the resort city of Acapulco, gunmen in army-style uniforms attacked two police stations, killing seven people, despite a military crackdown against violent drug gangs. Local media said men dressed in khaki uniforms and wearing red berets opened fire with automatic weapons at one station, killing three policemen. A man with the assailants filmed the attack with a video camera, the El Universal newspaper said. Hitmen also attacked another station, stripped several agents of their weapons and started shooting, killing a secretary, two police officers, and a public prosecutor. Local government officials said they were investigating but shared few details. "We don't know, we are still investigating," said local police director Erit Montufar. "Of course we have taken all precautions at the moment, our precautions are major but without overlooking our job, because we have to do it, because there is a lot of work to do." In a separate incident, gunmen killed a police chief in the northern city of Culiacan, Sinaloa (1200 kilometres north of Mexico City), spraying his vehicle with at least 100 shots. Police Chief Jorge Valdez Fierro was gunned down in the morning while on patrol in his vehicle. Police said that three cars with several people inside shot at the Culiacan officer dozens of times. Valdez Fierro worked as the coordinator of police investigations. He is the third police chief killed this year in Sinaloa, just four days after two soldiers were killed in Culiacan. The state of Sinaloa is known for a heavy presence of organized drug gangs. There have been no arrests in any of the three attacks. President Felipe Calderon, who took office on December 1, has sent thousands of troops to violent regions of Mexico to tackle drug gangs who killed 2,000 people in a feud last year. In January, almost 8,000 troops and federal police were sent to the region around Acapulco-- once-glamorous resort made famous by Hollywood stars in the 1950s-- to clamp down on rival gangs at war for control of lucrative drug plantations and smuggling routes. There were 190 drug gang-related deaths in Mexico in January, just a handful less than a year ago, despite the crackdown. Calderon called an emergency meeting with his security cabinet to discuss the attacks.