An 11-year-old boy was flown to hospital after a crash on the A85 Oban to Tyndrum road on Sunday afternoon.
The youngster was taken by helicopter to the Royal Hospital for Children, while three other people were taken to hospital by ambulance.
Their conditions are currently not known.
The road was closed at 2.45pm for 10 hours while a police investigation took place.
The fire service from Killin and Oban were also in attendance and helped to free passengers from two vehicles.
Road policing officers are now appealing for information following the crash which happened near to the Oban turn-off from Tyndrum.
Oban to Tyndrum road was closed for 10 hours
A police spokesperson said: “At around 2.45pm on Sunday February 4, police were called to a two-vehicle road crash on the A85, around five miles west of Tyndrum
“The crash involved a grey Dacia Duster and a grey Citroen C4.
“Emergency services attended and three people were taken to hospital by ambulance.
“An 11-year-old boy, was taken to the Royal Hospital for Children in Glasgow by helicopter.
“The road was closed for around 10 hours.”
Sergeant Scott Miller said: “Inquiries into this incident are ongoing and we are looking to speak to anyone who was in the area at the time and saw what happened or saw the vehicles before the crash.
“I’m also keen to hear from anyone with dash cam or any other footage of the area shortly before 2.45pm on Sunday.”
Anyone with information should contact Police Scotland on 101 quoting incident number 1176 of 4 February, 2024.