Attackers dressed as police officers opened fire in a bar in Mexico's northern Chihuahua state, killing 11 people, authorities said.

Police were searching for the trucks used in the attack, which were caught on the bar's security cameras.

At least 19 people died in separate attacks overnight in Chihuahua State, Mexico's most violent, including four police.

Suspected drug-related attacks have claimed almost 3,500 lives so far this year across Mexico.

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