Three chimpanzees have been killed in an ongoing containment attempt by Swedish zoo authorities after a group of apes broke out of their enclosure at Furuvik Zoo on Wednesday. Four chimps were still loose in the monkey house as of Thursday, including one that was wounded but unable to be treated amid the chaos, according to authorities. So far, staff haven’t been able to corral or even locate the three uninjured chimps to return them to their enclosures. “Our focus right now is to get an overview of where the four are now so that we can start working on getting them back to their enclosures in a safe way,” Annika Troselius, a spokeswoman for the zoo, told Swedish news outlet SVT. Zoo officials resorted to shooting the animals in lieu of tranquilizers as there was not enough tranquilizer for all of them, according to The Atlanta Journal-Constitution. A conservation expert with the World Wildlife Fund described the situation as “incredibly sad and tragic,” adding that “this should never have happened,” according to Swedish news outlet SVT.