The crash is considered one of the deadliest traffic accidents in Europe for a decade.
Relatives waited outside Pirogov hospital in the Bulgarian capital Sofia where their loved ones were being treated following a deadly bus crash early on Tuesday.
The bus crash and subsequent inferno, which left at least 44 people dead, has left little room for hope.
Only four men and three women – including a 16-year-old girl – survived the crash after breaking one of the windows and jumping to safety, according to officials.
The crash has been considered one of the deadliest traffic accidents in Europe in a decade.
"I only know that my uncle, a 49-year-old from the village of Dolno Kolichani, is well, in stable condition. He only has some scratches on the face but this is nothing, he's not in danger," said Bajazidovski, one of the relatives waiting to hear from the rest of his family.
His uncle survived the crash, but he has not heard about his aunt and cousin.
"For my aunt and cousin, we don't have any definitive information. But doctors say that if they are not here, the chances are that they died at the site of the accident," he added.
The government in North Macedonia has called for three days of national mourning following the accident.
Although the cause of the crash has yet to be determined, officials believe the bus swerved off the motorway and tore a 50m section of the crash barrier.
But it is not yet known if the bus caught fire before or after the crash. No other vehicles were involved in the accident.
Those who died trapped in the burning bus – including four-year-old twins, according to media reports – were mostly tourists returning from Istanbul in Turkey to Skopje in North Macedonia.
The flag of the Republic of North Macedonia will be flown at half-mast. Bulgaria has also declared a day of mourning on Wednesday.
"We are together with our North Macedonian brothers and grieve together in this tragedy. We hope the survivors recover swiftly," said Bulgaria's President Rumen Radev.
EU chief Ursula von der Leyen sent her "deepest condolences to the families and friends of those who perished in the tragic bus accident" and wished "a fast recovery to those injured".
"In these terrible times, Europe stands in solidarity with you," she went on.
Russian President Vladimir Putin also expressed his "sincere condolences" and said he hoped for "the speedy recovery of all those wounded".
'I lost my whole family'
The victims have not yet been officially named, but officials said they include 12 children, and many young people aged between 20 and 30.
Media in North Macedonia reported that several of the dead were from a Skopje primary school, where all classes were stopped.
"I lost my whole family in the blaze," one man told local media, saying 10 of his relatives had died.
Twenty Bulgarians died in 2018 when their bus skidded on a wet road and overturned.
A total of 628 people died in road accidents in 2019 and 463 in 2020 in Bulgaria, according to official data.
The accidents were often attributed to poor road conditions, outdated cars, and speeding.
Tuesday's accident occurred on a section of highway with steep gradients and without clear demarcation lines.
Many accidents have taken place there in the past, said road safety activist Diana Roussinova, whose organisation has already complained to authorities about the stretch.