IGUALA, Mexico - Gunmen posing as public officials stormed a prison in southwestern Mexico on Friday, sparking a shootout that left five of the assailants and four inmates dead, officials said.Six armed men entered the prison in the Guerrero state town of Iguala by fooling a guard into thinking they were delivering an inmate some time after midnight, police and prosecutors said.“Once in the prison, the armed group started a confrontation against inmates and later against guards in a security tower,” the state prosecutor’s office said in a statement.The sixth assailant was wounded in the attack. A prison guard was also hospitalized with a bullet wound.State authorities and army troops restored order in the prison, the prosecutor’s office said. Federal police were deployed around the prison.Authorities were investigating the motive behind the attack. Police seized a stolen pick-up truck that had been used by the assailants.A state police official, speaking on condition of anonymity, said the assailants were carrying heavy-caliber weapons.One of the dead inmates was a convicted cocaine dealer, another was a kidnapper and the two others were imprisoned for carrying illegal weapons. Three were in their 20s and one was 41 years old.Guerrero is home to the fabled beach resort of Acapulco but also high poverty and crime.It has become the deadliest state in Mexico, with 2,310 murders in 2012 and 1,916 in the first 11 months of 2013 amid deadly turf battles between drug gangs.The National Human Rights Commission said in November that violence has increased in Mexico’s prisons.The commission found in an annual report that 65 of the country’s 101 most populated prisons were under the control of convicts in 2012, a 4.3 percent increase from 2011.The commission said the number of riots, fights, escapes and homicides had increased, with 73 acts of violence that left 154 inmates dead and 103 wounded. Another 261 inmates escaped.In the latest prison break, officials in the central state of Morelos said four inmates escaped from their cells in the town of Xochitepec early Friday.A Morelos state public security official told AFP that the fugitives used a rope and a ladder to climb one of the prison’s towers and jump a wall with the help of a guard.The four convicts had been imprisoned for kidnapping and carrying illegal weapons.Guards are often involved in prison breaks in Mexico.In September 2012, 132 inmates snuck out of the front door of their facility in Piedras Negras, a city near the US border in the northern state of Coahuila.The prison’s director and security chief were detained following the mass prison break, which the Zetas drug cartel was suspected of masterminding.Mexico’s ombudsman Raul Plascencia Villanueva said in November that the overpopulated penitentiary system was in “critical condition.”More than 239,000 people are housed in Mexican prisons, exceeding capacity by 45,000 inmates.