The city prosecutor's office said in a statement that six persons including a woman were killed, while two women and a man sustained injuries, as a result of the shooting on Sunday in the Los Reyes Culhuacan neighbourhood of Iztapalapa, Xinhua reported.
A group of people was drinking at a party outside a church when four persons approached them and opened fire, reports in Mexican media mentioned.
The shooters fled the scene and authorities are reviewing videos from security cameras nearby.
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The prosecutor's office has launched an investigation into the incident.