It resulted in a 38-year-old woman and two children, aged four and six, being taken to Aberdeen Royal Infirmary with serious but non-life threatening injuries.
A 31-year-old man and two children, aged one and three, were also taken to hospital with minor injuries, Police Scotland said.
Meanwhile, three men, aged 66, 75 and 76, were treated by emergency services at the scene.
Road Policing Sergeant Steve Manson said: "Our thoughts are with those involved and their families as they recover from their injuries.
"The incident involved a number of vehicles, resulting in the road being closed for five hours.
"We are appealing for anyone who witnessed the collision or was in the area around the time and may have dashcam footage to contact Police Scotland."