Twelve labourers died when boulders crashed into them following a blast in a quarry at Agraharam in Aluru mandal in the district on Friday. According to information reaching here, all the victims were from Odisha. A few more labourers who were injured were rushed to a hospital. The quarry is understood to be owned by one Srinivas Chowdary. The sources said that a house nearby collapsed due to the impact of the blast.