Kuba, a 16-year-old male lowland gorilla, died Monday morning at the Topeka Zoo during a chemical immobilization.
Kuba died at about 8 a.m. as staff members from the zoo and Manhattan's Kansas State University School of Medicine prepared him to be loaded onto a vehicle and transferred to Erie Zoo in Erie, Pa., said Topeka Zoo director Mike Coker.
"We gave him the drug, and he went into cardiac arrest," he said.
Results weren't available late Monday from a necropsy being conducted at K-State to determine Kuba's cause of death. Coker said a full report would be presented when it became available.