WASHINGTON — The 170-pound giant panda cub at the National Zoo grabbed a worker while trying to play, sending her to the hospital with a small leg laceration, zoo officials said Wednesday.

The panda apparently entered his yard through an unsecured door Tuesday during a routine feeding, zoo spokesman John Gibbons said.

Jacquelyn Martin/AP (ENLARGE)

In this photo from 2007, Tai Shan, the National Zoo's popular giant panda cub, munches on bamboo. These days, he weighs in at 170 pounds.

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The keeper was treated at a hospital and released. The incident is being investigated.

The keeper took 2-year-old Tai Shan indoors before placing food in his yard, Gibbons said in a statement. The panda re-entered the yard and approached the keeper from behind, playfully grabbing her with his mouth, Gibbons said. Pandas have sharp teeth, used for chewing bamboo.

"The keeper was able to radio for help, and other animal care staff distracted Tai Shan with food as they also safely assisted the keeper out of the yard," Gibbons said.

Keepers stopped entering the panda cub's yard with him for safety reasons when he reached about 70 pounds, Gibbons said.

Tai Shan, whose name means peaceful mountain, was born July 9, 2005. He is the first giant panda born at the National Zoo to survive more than a few weeks. The mother, Mei Xiang, and the father, Tian Tian, are on a 10-year loan from China. The cub will remain at the zoo at least until 2009.

Only about 1,600 giant pandas remain in the wild, and fewer than 180 live in captivity.

• For more information: http://nationalzoo.si.edu/Animals/GiantPandas/