A bus from Serbia crashed in Bulgaria on Sunday evening, injuring children and adults who were on board. The crash happened in the southern Bulgarian city of Stara Zagora, transmits MIA.

The bus was driving towards the capital Sofia when it left the road and overturned in a ditch. Eight children and four adults were taken to hospital, some with serious injuries, the Bulgarian Interior Ministry said.

Others were examined and given medical treatment as necessary. Driver error was suspected to have caused the accident when the driver’s attention had been diverted on the bus, Interior Minister Ivan Demerdzhiev told broadcaster bTV.

The bus was on its way from Bulgaria’s Black Sea coast to Belgrade with 38 children and 10 adults from Serbia on board, he said. The children were taking part in a folklore festival in the seaside resort of Slanchev Bryag (Sunny Beach). Investigations were due to start overnight.

The accident comes just over a week after a serious accident with a bus from Romania that killed four people.