Emergency services were called to the scene near Dunkeld, Perth and Kinross, at about 2.30pm on Tuesday.
Police said that one person has died.
The road has been closed in both directions while officers deal with the incident.
A Scottish Fire and Rescue Service spokesman said: “The Scottish Fire and Rescue Service was alerted at 2.31pm on Tuesday, May 22 to reports of a road traffic collision involving three vehicles on the A9 near Dunkeld.
“Operations control immediately mobilised a number of fire engines.
“Crews left the scene after ensuring the area was made safe.”