In pictures: Strong earthquake shakes Croatia

A search for survivors in Croatia stretched into the night Tuesday after a powerful earthquake killed at least seven people in the country's interior, tearing down rooftops and piling bricks in the streets. | Above: People clean debris from a street after the earthquake, in Petrinja.

The 6.4-magnitude quake was felt as far afield as Vienna but the heavy damage was concentrated in and around Petrinja, a town of around 20,000 some 50 kilometres south of Croatia's capital Zagreb.

Rescue teams shovelled away debris in search of victims as night fell after the mid-day tremor, while the European Union announced that more help was on its way.

Prime Minister Andrej Plenkovic said late Tuesday that seven victims had been found so far and that there would "probably be more".

Among the dead was a young girl in Petrinja, reported to be 12 years old, and at least five people in a nearby village, according to Croatian police, who said that around 20 people were injured.

Six people were rescued from the rubble with the help of dogs, Croatia's Mountain Rescue Service said.

Many in Petrinja were afraid to return home at night in fear of aftershocks, while damage from the quake left most of the buildings in the downtown area "unfit for use", according to construction experts.

"All the tiles in the bathroom are broken, all the dishes fell out," Marica Pavlovic, said a 72-year-old retired meat factory worker, of the damage to her apartment. "Even if we wanted to, we can't go back in, there is no electricity," she said, huddled with others in a downtown park, wrapped in blankets.

"The city is actually a huge ruin," Petrinja's mayor Darinko Dumbovic told national radio. "We are saving people, we are saving lives. We have dead people, we have missing people, injured people... it is a catastrophe."

The earthquake, which hit around 1130 GMT according to the US Geological Survey, rattled Petrinja and the surrounding area just a day after a smaller earthquake struck in the same vicinity, causing some damage to buildings.

Military personnel load an ill person on a stretcher onto a helicopter to be evacuated to Zagreb, after an earthquake, at a military base in Petrinja.

The mother, left, no name given, of 12-year old Laura who was killed by falling rubble during the earthquake, reacts next to buildings damaged in the quake in Petrinja.

The tremors reverberated across neighbouring countries, including Serbia and Slovenia, which as a precaution shut down the Krsko nuclear power plant it co-owns with Croatia.

An ill person is carried out from an ambulance to be evacuated to Zagreb by helicopter, at a military base in Petrinja.

The rubbles of damaged buildings in Petrinja.

A picture shows a crack on the road in Petrinja.

A man stands next to his damaged car and damaged buildings in Petrinja.

A fire truck next to damaged buildings in Petrinja.

A man inspects damages on a building in Petrinja.