A grey Mazda 3 series, a blue Volvo S60 and a white Mercedes A-Class were involved in the crash.
All three drivers were taken to Raigmore Hospital in Inverness for treatment.
Officers are now appealing for witnesses to come forward to assist with their investigation.
PC Neil Macdonald, from Alness Police Station, said: “Our inquiries are ongoing to establish the full circumstances of the crash.
“I would urge anyone who was driving in the area at the time who has a dash-cam attached to their vehicle to review their footage and come forward with any information that may assist with our investigation.
“I would also urge anyone who witnessed the crash who has not yet come forward to contact police via 101, quoting incident 2434 of April 5, 2022.”
Appeal after three drivers hurt in A9 crash near Alness