"Once you've done all of those things ... if they don't respond there's really nothing you can do. You've exhausted the playbook," he said.
After 15 minutes of unsuccessful treatment, doctors pronounced him dead.
"We did everything we could" to try to save his life, Schoenfeld said.
How did the medical team react to treating the bombing suspect?
"There was some discussion in the emergency room about who it was. That discussion ended pretty quickly," Schoenfeld said. "It really doesn't matter who the person is. We're going to treat them as best we can."