A bus crash occurred on Trakia motorway at the 217th kilometre point in the direction to Sofia on August 14.
It was a bus with Serbian registration, which was taking children and adults from a holiday on the Black Sea coast, the Ministry of interior said.
There was a total of 49 passengers - 38 children and 11 adults. They managed to get out of the bus by breaking the front and rear windows.
There is no evidence of an external cause for the accident, the caretaker Minister of Interior told BNT.
46 passengers were injured and taken to hospital, 17 of whom are in the emergency centre in the city of Stara Zagora, Southern Bulgaria. Three passengers escaped uninjured.
Three children have multiple cuts and bruises and will be receiving a scan examination. One adult male is in a more serious condition.
The bus driver was also injured.
Initial indications are that there are no fatalities. A corridor was set up on the motorway to afford free passage of the injured to the hospital in Stara Zagora, which is the nearest.
The bus had rolled on to its side into a ditch on the motorway. The cause of the crash could not yet be ascertained, the Ministry of Interior told BNT.
Police and firefighters attended the scene, traffic in the area was disrupted.
Passing motorists stopped and provided assistance to help the injured out of the bus.
The incident happened shortly after 8 pm.
The authorities are investigating the possibility that the cause was a slippery road surface, or driver falling asleep at the wheel.
The children were travelling from the Bulgarian seaside town of Nessebar. They were part of the folklore ensemble "Julira" and are from the Belgrade suburb of Batajnica.
By order of Bulgaria’s Prosecutor General, Ivan Geshev, a team of investigators from the National Investigation Service took over the investigation of the crash.
"Information is scarce, the investigation has been assigned to the National Investigation Service," Supreme Cassation Prosecutor's Office prosecutor, Siyka Mileva, who is a spokesperson for the prosecutor general, told BNT.
According to road safety expert Diana Rusinova, there is a violation of Bulgarian law in this case, as children are not allowed to be transported during the dark hours of the day.
"The bus entered the territory of Bulgaria through Kalotina checkpoint on 7 August at 23:00. It was travelling in the direction of the Bulgarian Black Sea coast, today, august 14 was the return journey to the Republic of Serbia. There were 49 passengers on the bus, 46 of them were transported by the teams of the Emergency Medical Aid to the centres in Stara Zagora. 3 persons are waiting on the spot and are in good condition," Deputy Secretary General of the Ministry of Interior, Stanimir Stanev, told BNT.
"Everything was great before the crash, a man wanted to sit next to the driver, because he wanted the driver to show him how to lower the seat. We leaned to the right. The had had enough sleep before getting behind the wheel. We were in Sunny Beach resort, from there we departed for Serbia, we stopped at a petrol station. We were 48 people plus the driver - 38 children and 10 adults. There is a speed limit, you can't drive fast. It was scary with the small children," one of the passengers from the bus told BNT.
An inspection of the crash site has begun. The bus driver is in the hospital in Stara Zagora, he was not seriously injured and is to be taken for questioning. "According to initial information, between 8 and 9 children are more seriously injured, examinations are underway," Nikolai Kolev, director of the Ministry of Interior’s regional directorate in Stara Zagora, told BNT.
Traffic was temporarily stopped at Sliven in the direction to Sofia to ensure the passability of rescue teams.