At least 46 people, most of them tourists from North Macedonia, have been killed in a fiery bus crash in western Bulgaria, officials said.
Twelve children were among the victims, the head of the General Directorate of the National Police, Stanimir Stanev, told bTV.
Seven survivors were rushed to hospital in the capital, Sofia, and were being treated for burns.
It was not immediately clear what caused the crash, which occurred shortly after 2 a.m. near the village of Bosnek, about 31 kilometers southwest of Sofia.
Some reports said it appeared the bus had hit a highway guard rail, crashed, and caught fire.
"It was probably a technical malfunction or a flat tire," Nikolai Nikolov, head of the General Directorate for Fire Safety and Protection of the Population at the Interior Ministry, told bTV.
Bulgaria’s government declared a day of mourning on November 24, while there will be three days of mourning in North Macedonia during which flags will be lowered to half-staff and all public events will be canceled.
The bus was one of four traveling together from Istanbul to Skopje in North Macedonia.
Photos taken shortly after the crash showed the bus engulfed in flames with thick plumes of smoke blanketing the highway in both directions.
Media in North Macedonia later reported that police went to the Skopje offices of a travel company that is believed to have organized the trip to Turkey. No further details were immediately available.
Interior Minister Boyko Rashkov told reporters at the crash site that he had "never in my life seen something more horrifying."
"The picture is horrifying. The people who were on the bus are turned to charcoal," Rashkov said. "It is impossible to say how many there were. There were four buses that traveled together, and it is possible that passengers changed buses during the stops."
Bulgaria's caretaker prime minister, Stefan Yanev, visited the site of the crash, which he called a "huge tragedy."
"I take this opportunity to send my condolences to the relatives of the victims," Yanev said. "Let's hope we learn lessons from this tragic incident and we can prevent such incidents in the future."
North Macedonia's Prime Minister Zoran Zaev told bTV that he had spoken to one of the bus survivors.
“One of the passengers told me that he was asleep and woke up from an explosion,” Zaev said, adding that the authorities will gather information that is “important for the families of the dead and the survivors.”
Zaev, who arrived in Bulgaria to visit the survivors in the hospital, said the passengers were all from North Macedonia but appeared to include a Serbian citizen and a Belgian citizen. It was unclear whether the two were among the victims or the injured.
In a statement posted on Twitter, Stevo Pendarovski, North Macedonia's president, called it a "horrific accident" and said that he expects the authorities to conduct a full investigation to determine the "causes and responsibility for the tragedy."
European Commission President Ursula von der Leyen expressed her condolences to the families and friends of those who died in the "tragic bus accident" and said that "in these terrible times, Europe stands in solidarity with you."
Those sentiments were echoed earlier by European Union Commissioner Oliver Varhelyi.
"Terrible news about the tragic bus accident in Bulgaria in early morning hours," Varhelyi wrote online. "My thoughts & condolences are with the families and friends of those who died as well as with the people and the authorities of North Macedonia."
Bulgaria, an EU member of some 6.9 million people, has seen many deadly bus accidents over the past several years. In the most recent one, 17 Bulgarian tourists died in 2018 when their bus skidded on a wet road and overturned.
The accidents are often caused by poor road conditions, old vehicles, and speeding.
A total of 628 people died in road accidents in 2019 and 463 last year in Bulgaria, according to official data.