At least 45 people died when a bus caught fire and crashed on a highway in western Bulgaria on Tuesday, officials and local news outlets said.

The bus had North Macedonian plates, and most of the victims were from that country, BTV television reported, citing an official from the North Macedonian Embassy in Sofia, the Bulgarian capital.

Nikolai Nikolov, the head of the fire safety department at the Bulgarian Interior Ministry, told BTV that 52 people had been traveling on the bus when it crashed around 2 a.m. local time. BTV said the accident occurred on the Struma Motorway near the village of Bosnek as it was traveling from Sofia to Blagoevgrad.

North Macedonia’s foreign minister, Bujar Osmani, told BTV that the bus had taken a trip to Istanbul over the weekend.

“At least 45 people were killed after a bus caught fire and crashed, or crashed and then caught fire,” Mr. Nikolov was quoted as saying, according to Reuters. He added that children had been among the victims.

Some people jumped through the bus’s windows to escape the flames, local news outlets reported. Seven people with burns and lacerations were taken to a hospital in Sofia, Maya Argirova, head of the burn clinic in Pirogov Hospital, told reporters.

Additional details were not immediately available.

On Tuesday, the minister for foreign affairs of Bulgaria, Svetlan Stoev, and Mr. Osmani of North Macedonia spoke by phone, according to a release posted on Bulgaria’s site for the ministry of foreign affairs. Mr. Osmani was en route to the Pirogov Hospital, where he would meet with Mr. Stoev, according to the release.

On Twitter, Mr. Stoev said that Bulgaria would do everything to take care of the victims and find the cause “of the tragedy.”

Zoran Zaev, the departing prime minister of North Macedonia, expressed condolences to the families of the victims, BTV reported.

“I am horrified by the tragedy, I am sorry for the incident,” said Mr. Zaev, who had announced in October that he would step down as prime minister and leader of his center-left party, the Social Democratic Union of Macedonia, after a defeat in local elections.

Stefan Yanev, the acting prime minister of Bulgaria, who visited the site of the crash, told reporters, “This news shook us and demanded that the Bulgarian state react very quickly and make it possible to investigate this road accident.”

In 2018, a tourist bus carrying 33 pilgrims from a village north of the capital to a monastery crashed near Sofia, killing at least 16 people and injuring 26 others.