A cistern collapsed at a banana farm in the southernmost province of Hainan early Saturday morning, claiming six lives, said local authorities. The mishap occurred when the walls of a cistern collapsed and destroyed a makeshift worker shed built next to it at a banana plantation in Licai Farm, Xinhua quoted Head of the Sanya Municipal Work Safety Bureau Zhou Naiwu as saying. Six adults and an 11-month-old baby girl were sleeping in the shed. The adults, including four workers from Guizhou province and two local guards were killed, while the baby was hurled out of the shed by water and survived, Zhou said. An investigator said the accident was most likely caused by rain-triggered geological changes that cracked the wall of the cistern. The cistern was built in April last year with a volume of 144.5 cubic meters. One man has been detained for questioning by local police.