Ellen, being a former tech at a primate lab, will probably find this story grim but unsurprising:

Several chimpanzees broke from their cages at an animal sanctuary Thursday and attacked two visitors, seriously injuring them, authorities said. Sanctuary workers shot and killed two of the powerful animals.

Officials did not immediately release the victims' names, but a television station reported that they were a couple who were visiting another chimpanzee that had been removed from their home years earlier for his own aggressive behavior.

Every primatologist I've spoken with or read has remarked that chimps are unusually excitable primates, most often compared to three year old humans. They tend to, well, freak out. In a toddler, this can be amusing. In a 150-pound-plus creature that is nearly as smart and can unscrew your head with its bare hands, not so much.