Survivors of the suicide bomb blast said passengers were forced to jump out windows as the bus filled with thick black smoke after the explosion.
One lady on board told how her grandchild's quick thinking saved her and her daughter.
"I sat two rows from the back there was a large explosion, very strong, all the windows broke and the glass hit us. After we got ourselves together my grandchild told me 'let's jump out of the window'. So he jumped out and my daughter jumped, as I was about to jump out I saw smoke starting to fill up the place and it was becoming impossible to leave. I knew if I stayed inside it would blow up, so I also jumped".
The death toll was raised to at least eight after the Bulgarian driver of the bus died in hospital overnight.
