The National Zoo has begun to fill staff vacancies that contributed to the deaths of three animals and a zebra attack on a zookeeper last winter, zoo officials told a congressional oversight committee.

Zoo spokeswoman Pamela Baker-Masson said the zoo has hired seven animal caretakers and has plans to hire an additional 10 people for various other jobs. The zoo’s staff had been “spread too thin,” Baker-Masson said.

“Some of the problems that arose reflected some staffing imbalances that, while temporary, did put stress on the system,” National Zoo Director Dennis Kelly and Smithsonian Conservation Biology Institute Director Steven Monfort said Wednesday in a statement to the Committee on House Administration.

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