At least 45 people, including 12 children, were killed when a bus carrying North Macedonian tourists caught fire hours before dawn on a motorway in western Bulgaria.

Hospital workers said that seven individuals who jumped from the burning bus were transported to a hospital in Sofia. They were in stable condition. According to Bulgaria's interior ministry, 45 people perished in the bus tragedy, making it the deadliest Balkan country's history.

Interior Minister Boyko Rashkov stated that the victims had been "clustered inside and are burnt to ash."

"The image is harrowing, harrowing. I've never seen anything quite like it "he explained to reporters on the scene.

The reason for the accident remained unknown, although officials in Bulgaria said the bus looked to have collided with a highway barrier either before or after catching fire.

Bulgarian officials reported that the accident occurred around 2:00 a.m. on the Struma motorway, about 45 kilometers west of Sofia. The coach party was returning to Skopje after a weekend vacation in Istanbul, a journey of around 800 kilometers.

According to a television video, the bus was burnt and consumed by fire in the middle of the wet highway.

"We have an enormous tragedy here," interim Bulgarian Prime Minister Stefan Yanev told reporters.

North Macedonian Prime Minister Zoran Zaev stated that he spoke with a survivor who noted that the passengers were sleeping when the sound of an explosion awoke them.

"I am frightened. This is a monstrous disaster "he said BTV, a private television station.

Borislav Sarafov, head of Bulgaria's investigative department, said four buses from a North Macedonian tourist operator entered Bulgaria late Monday from Turkey.

"Human mistake by the driver or a technical malfunction are the two initial versions for the accident," he explained.