JOHANNESBURG (AP) — The parents of the American student mauled by two chimps in South Africa last week called their son’s survival a “miracle” and thanked doctors for their work.

The statement on Friday said Andrew Oberle was stable but remains in critical condition.

A hospital spokeswoman Martina Nicholson told The Associated Press the hospital will not release any information about the victim. His parents say they might release further statements.

Oberle was transferred to a Johannesburg hospital on Thursday after being treated in eastern South Africa where he was injured June 28.

Oberle was mauled by two adult chimps in a South African chimp sanctuary where he was doing research. A state investigator says Oberle lost fingers and sustained head and other injuries.