Nine people were killed, including four women, after gunmen entered a bar and opened fire in Mexico’s violence-plagued Guanajuato region, local media reported.

It was the third massacre in as many months in Guanajuato, where a local gang is at war with the Jalisco cartel. The attackers tried to kill everyone present in the bar, including the waitresses.

The attackers left handwritten posters on the bar’s blood-soaked floor. The messages were signed by the Santa Rosa de Lima gang, whose now-imprisoned leader is known as “Marro” or Barosul.

Reports accused the bar’s owners of supporting the rival Jalisco cartel.

Photos from the scene show the bodies of several waitresses passed out in pools of blood in the bar.

Municipal authorities in Apaceo el Alto said two other women were injured in the attack but are in stable condition.

In October, 12 more people, half of them women, were killed in an attack on a bar in another city, after 10 people were killed in a similar attack in September.

The people said the attacks targeted specific bars whose owners allegedly refused to pay security or bought drugs from rival gangs.

There are signs that the conflict in Guanajuato, Mexico’s most violent state, is actually a battle between two of Mexico’s most powerful drug cartels. It appears that the Sinaloa cartel is supporting the Santa Rosa de Lima gang in their fight against Jalisco.