BELGRADE, Serbia — A concrete roof above the entrance of a railway station in the northern Serbian city of Novi Sad collapsed Friday, killing at least eight people.

Interior Minister Ivica Dacic said that at least four other people have been hospitalized with serious injuries, while rescuers have established contact with two people who are still buried under piles of concrete.

Ambulances and other emergency teams were dispatched to the downtown station and bulldozers were removing the debris looking for survivors.

Surveillance camera footage showed people moving in and out of the building and sitting on benches on a bright and sunny day before the concrete structure suddenly collapsed on them. The building was recently renovated.

Dacic said the rescue operation was “extremely hard” and that it would last for at least several more hours.

Serbian Prime Minister Milos Vucevic said “this is a black Friday for us, for all of Serbia.”

Vucevic said that the roof was built in 1964 and an investigation is underway to determine what happened and who is responsible for the tragedy.