File picture: SAPS Twitter.

Mexico City - Unidentified gunmen stormed a party in the south-eastern Mexican state of Veracruz and killed 13 people, including a young child, according to reports.

The attack occurred late Friday as a children's party was under way in the city of Minatitlan, the broadcaster Telemundo reported.

Seven other people were injured, the reports said. Most of the victims are said to have been from the same family.

Police said the the gunmen were still at large and their motives were unknown.

In a tweet, Veracruz Interior Minister Hugo Gutierrez Maldonado offered his condolences to victims' relatives and promised to catch the killers.

Veracruz is one of Mexico's most dangerous states, where cartels often engage in brutal battles. Last year, there were over 33,000 murders in the country, most of which were linked to organized crime.