At least 13 people were killed overnight Monday in the Brazilian city of Campinas, about 100 kilometers from Sao Paulo. Police said the victims, all men, were killed in four neighborhoods of the Campinas suburb of Ouro Verde. Three were rescued alive but died en route to hospital, dpa reported. Relatives of the dead said the killers were masked and travelled in two cars. The Public Security Ministry of the state of Sao Paulo said the motives for the killings were unknown. Investigators are trying to establish whether they were in fact linked to each other.