A video from the conference caught the deafening roar as the earthquake hit. The ground shook and people screamed and stumbled as Dumbovic looked on, momentarily stunned.
"Horrific," said Igor Sebo, who uploaded the video to social media. "The ground literally bounced."
As the footage continued, the camera swung around to reveal dust and debris as parts of buildings began to disintegrate.
Church bells, apparently shaken and swinging due to the quake, can be heard to ring out.
On Wednesday rescue workers were continuing to sift through the rubble of the earthquake that claimed at least seven lives, including wrecked buildinbgschildren.
Tuesday's toll included a young girl struck by falling debris on a street, a man who had tried to resuscitate her told local media.
Another victim was buried beneath rubble in a village church, a priest told state news agency HINT.
At least 20 people were injured, Croatian police said, while six survivors were rescued from wrecked buildings.
Neighbouring Slovenia's sole nuclear power plant in Vrbina, around 100km from Petrinja, was shut down after the tremor as a precaution.
Petrinja mayor Darinko Dumbovic looks stunned as the rumbling begins. Photo / Twitter/Igor Sebo
The quake, which was felt across the Balkans, shook buildings that had already been weakened by a moderate tremor in the same region on Monday. The Balkans lie near fault lines and see regular seismic activity.
Many in and around the hard-hit town of Petrinja spent a sleepless night in fear of new tremors. While hundreds sheltered in a nearby military barracks, others opted to stay in their cars.
"We go inside to quickly grab what we need and we return here," local resident Visnja, 66, told AFP. She was sitting around a fire outside her home in Petrinja on Wednesday morning after having slept in her car.
In the nearby village of Majske Poljane, the quake killed five people as well as mangling homes and farm buildings in the poor community.
"I can hardly wait for this horrible year to end … we have only one more day," whispered Silvana Velic, a 29-year-old mother of four huddled in the cold outside her damaged house.
Local volunteers delivered food, clothes and blankets to those in need, while civil protection workers promised containers or camping trailers for those unable to sleep at home.
The European Union said it was mobilising aid from other member states, including containers, winterised tents and heaters.
From the Vatican, Pope Francis expressed sympathy for the victims in the mainly Catholic country.
"I hope that the authorities of the country, with the help of the international community, will soon be able to alleviate the suffering of the dear Croatian people," he said.
