Mexican prison officials say that at least 159 inmates have escaped from a prison in Nuevo Laredo, a northeastern town near the U.S. border.
Officials say the inmates escaped early Friday through the main entrance. One police source said the method of escape points to complicity of prison guards. Reports say local, state and federal authorities are searching for the escapees.
The incident comes three months after 85 prisoners escaped from a facility in Reynosa, across the U.S. border from McAllen, Texas. In that case, Mexican officials looked into the possible involvement of two missing prison guards and 44 other employees in the escape.
The incidents follow a scandal in July, when authorities discovered that officials at another prison in the northern state of Durango had allowed convicts out of that facility to carry out revenge contract killings.
Separately, Mexican authorities say a car bomb exploded outside a police station near the northern city of Monterrey Friday, injuring two people. An official says the bomb was aimed at intimidating police.
Monterrey is the capital of the state of Nuevo Leon, which has witnessed much violence as rival drug cartels fight with each other over lucrative smuggling routes.
Spiraling drug-related violence in Mexico has left more than 30,000 people dead since President Felipe Calderon took office in late 2006 and began cracking down on the cartels.