The Polish bus that skidded off the A4 motorway in northern Croatia early on Saturday was manufactured in 2011 and was in roadworthy condition, Polish media said.

Although there is no official information yet about the cause and circumstances of the accident, in which 12 people were killed and 32 injured, the unofficial assumption is that the driver fell asleep at the wheel, the media said.

The Polish Ministry of Infrastructure said that the bus was manufactured in 2011 and registered in Poland and had passed all the tests required by law. It underwent a roadworthiness test in June this year.

Łukasz Jasina, spokesman for the Polish Ministry of Foreign Affairs, said that the bus was carrying 42 pilgrims and two drivers, and that all the casualties were Polish nationals.

The bus embarked on its journey to the Marian shrine of Međugorje, Bosnia and Herzegovina from the Marian shrine of Częstochowa, southern Poland on Friday. Among the pilgrims were three priests and six nuns.

“If I’m not mistaken, the driver is alive,” Jasina said, adding that he would have to check this.

The Polish Ministry of Foreign Affairs has set up a special telephone line for this accident, and the police have compiled a list of passengers on the bus and sent it to the Croatian authorities.