A gunman stormed a house party and killed at least 12 people and himself during New Year celebrations in the southeastern Brazilian city of Campinas late on Saturday, Reuters reported.
Police in the state of Sao Paulo said the shooter is believed to have been angry over a separation from his former wife, who was among those killed. Local media reports said the couple's 8-year-old son also died.
A police spokesman could not confirm the identity or age of those killed or whether a child of the shooter, who also remains unidentified, was among the victims.
A neighbor interviewed by the Globo television network said that he and family members heard blasts about a quarter to midnight but did not immediately recognize it as gunfire, not New Year fireworks.
Only when one of those shot ran into their property, bleeding and asking for help, did they realize that someone had been shooting. State police said they were called to the scene at 12:40 a.m. local time.