Nine people were killed and 19 others were injured when a minibus crashed into a truck on a highway in central Bulgaria on Friday, the interior ministry said.

The driver of the bus, which was taking a group of blind people back home after an excursion to the town of Dryanovo, was among the dead and some of the injured were in a critical condition.

The accident occurred soon after noon (1000 GMT) on the highway connecting Bulgaria’s capital Sofia and the Black Sea city of Varna, near the village of Mikre, some 130 kilometers (81 miles) west of Sofia.

The ministry said the injured were taken to hospital, but did not say how many of them were in a critical condition.

The causes of the accident have yet to be established but Bulgarian Prime Minister Boyko Borissov ordered the transport ministry to carry out a full inspection of the minibus involved, the ministry said.

Local media reported that there had been at least eight serious car crashes, killing 10 people, on the same stretch of road near Mikre since 2014.

Bulgaria, which has a population of 7.1 million, has the highest road death rate in the European Union. A total of 535 people died in accidents on Bulgarian roads in the first 10 months of 2017, interior ministry data showed.