Via the National Journal:
The 10-minute recording, from March 30, 1981, of the Secret Service’s “OSCAR” channel, which linked the Presidential Protective Division agents around Reagan with the agency’s “Horsepower” command post at the White House, begins with an agent announcing Reagan’s exit from the side door of the Washington Hilton hotel.
Then came the six shots, fired closely in a row. These aren’t heard on the tape. Agents were instinctively reacting; the sequence of events is now familiar to anyone who has watched it.
“Advise, we’ve had shots fired. Shot fired. There are some injuries, ahh, lay one on,” says one Secret Service agent.
The agents can be heard using the assigned codewords as they plan. “Do you want to go to the hospital or back to the White House?” one asks. “We’re going to Crown,” says another, “Crown” being code for the White House.
“Rawhide is okay,” one repeats, using the designation for Reagan. “Rawhide is all right.”
When the president starts to cough up blood, they change their course. “George Washington, fast,” one declares. “Get an ambulance, I mean, get the stretcher out there,” another says. “Let’s hustle.”
The National Journal also has a full transcript.