At least 45 people, including 12 children, were killed in a deadly bus crash in Bulgaria. The bus, which was carrying mostly tourists from North Macedonia, crashed and burst into flames on a highway in western Bulgaria on Tuesday.

Bulgaria's interior ministry said the accident was the most deadly in the Balkan country's history, given the number of people that died. Police said seven people that jumped out of the burning bus had survived and are now being treated at a hospital in Sofia.

Interior Minister Boyko Rashkov said the scene of the accident was a grim sight to behold as bodies were clustered inside, most of which were burnt to ash. Rashkov said the pictures of the accident were even more "terrifying." He added that he had never seen anything like that before.

Police are still trying to determine the cause of the crash, but they believe the bus may have caught on fire before it hit a highway barrier. The collision demolished a portion of the highway barrier. The area surrounding the Struma road accident on Tuesday has been cordoned off by authorities as investigations continue.

Investigators are considering either human error or a technical malfunction as the two likely causes of the deadly crash.

Bulgarian officials said the accident occurred on the Struma highway just 28 miles west of Sofia at around 2:00 a.m. in the morning on Tuesday. The bus was returning to Skopje from a weekend trip to Istanbul. The journey was around 500 miles in total.

Bulgarian investigative service chief Borislav Sarafov said the bus was part of a four-vehicle fleet owned by a North Macedonian travel agency. All of the agency's buses had traveled to Bulgaria late Monday from Turkey.

Footage of the aftermath of the crash showed the bus gutted by the fire and lying in the middle of the highway. Firetrucks, ambulances, and police were also all on the scene of the accident.

Bulgarian interim Prime Minister Stefan Yanev expressed his dismay in what he called an "enormous tragedy." North Macedonian Prime Minister Zoran Zaev said he had spoken to one of the survivors, who told him that most of the passengers were asleep when the accident happened. He claimed that the survivor told him that they were all suddenly awakened by a huge explosion.

The passenger said he and six other passengers managed to break the windows of the bus. He claimed that if they hadn't jumped out of the bus, they would have also been burned and killed.