Dickerson Park Zoo zookeeper killed by elephant 11 October 2013 Last updated at 23:01 An elephant named Patience with a history of aggression has killed a veteran keeper, the zoo in the US state of Missouri has said. John Bradford, 62, elephant manager at Dickerson Park Zoo in Springfield, was working with the 41-year-old female. Patience suddenly moved, fatally injuring him, the zoo said. She will not be disciplined, the zoo said. Recently, the zoo euthanised the herd's matriarch, Pinky, who had advanced kidney disease. "This is a very sad day for the zoo family, as well as our community as a whole," Mike Crocker, director of the zoo, said in a statement. The zoo said zookeepers had kept a close watch on Patience and another female in the zoo's herd since Pinky's death. Two other zoo employees were with Bradford when he was killed, out of caution over Patience's history of aggression. Officials cannot determine why the elephant, who had been at the zoo since 1990, moved suddenly at Bradford. "This has never happened before," Springfield city spokeswoman Cora Scott told the BBC. There are counsellors on hand for the park employees, as it is a pretty tight-knit family here. Bradford had worked at the zoo for 30 years, 25 as elephant manager. The park remains open, though the elephant exhibit has been closed.