A Martinez boy who has been waiting for a lung transplant in St. Louis since August underwent surgery Wednesday night.

The double-lung transplant for Sawyer Mobley, 10, was scheduled for 4 p.m. at the St. Louis Children’s Hospital, but the operation didn’t start until later that night, an aunt told a reporter. His condition was not available late Wednesday.

Debbie Callan, a retired teacher who has been active in the efforts to raise funds for Sawyer’s transplant and related expenses, said the first 48 hours after surgery were critical.

Sawyer has battled cystic fibrosis since he was a newborn. His condition deteriorated quickly after catching a common virus in the summer. Sawyer is on oxygen 24 hours a day.

Sawyer and his mother, Angel, left for St. Louis in late August awaiting the transplant.