The Smithsonian's National Zoo shut down its Kid's Farm exhibit after E. coli was found in some animals.
National Zoo spokeswoman Pamela Baker-Masson says the area is now under quarantine and will be closed.
Veterinarians detected the E. coli stx1 bacteria in goats after a screening process on Feb. 18 and moved the goats away from visitors. Veterinarians conducted individual tests Friday and confirmed the goats and a cow tested positive for the bacteria.
All the animals are being treated with antibiotics. The exhibit will remain closed until zoo keepers have three weeks of negative tests from the animals.
Zoo officials say staff members have not been affected.