The earthquake felt especially strong in Zagreb and there are reports that it was felt in Rijeka, Vukovar, Split, across the country.
According to the EMSC, the power was 6.3. After that earthquake, another smaller one was felt.
According to the EMSC, the epicenter was 46 kilometers southeast of Zagreb, somewhere around Petrinja town.
Multiple reports from different city state that mobile phone networks are not working.
UPDATE
The Croatian army is moving towards Petrinja, at least 300 soldiers are arriving.
Petrinja Mayor Darinko Dumbović in his first statement after another strong earthquake of magnitude about 6.3, which hit Petrinja at around 12:20 local time, said that half of the city had been destroyed and asked for urgent help to be sent to Petrinja.
"We are pulling people out of the car, we don't know because we have dead and wounded, I also heard that the kindergarten collapsed, but fortunately there were no children in the kindergarten," Dumbovic said.
"There is a general panic, people are looking for their own," he added, calling on everyone who can come to Petrinja's aid, especially professional firefighters and the army.
In a live statement for N1, Mayor Dumbović said that he had heard the Prime Minister Andrej Plenković on the phone, who confirmed that he was leaving for Petrinja.
According to information, one child was killed in Petrinja and the mother next to him is crying inconsolably.
A strong earthquake that hit Croatia on Tuesday was felt throughout Slovenia and the operation of the Krško nuclear power plant was stopped as a precaution.
The power plant is built to be resistant to much stronger earthquakes than those recorded so far in Slovenia or Croatia. Its construction would withstand an impact of 7.9 degrees.
Reports are coming the earthquake was felt in neighboring countries, from Serbia to Italy.
Hrvatski Telekom (Croatian Telecom) urged citizens to use lines responsibly to enable first responders to answer the calls.
"This has nothing to do with life. My city is completely destroyed. We have dead children. It cannot be described. This is like Hiroshima. We need firefighters, we don't know what's under the surfaces, the house roof fell on a car, we need help," Petrinja Mayor Darinko Dumbović told Croatian television HRT.
"A 20 year old boy from Majske Poljane died, his house collapsed on him," Glina Deputy Mayor Branka Bakšić Mitic confirmed to 24sata newspaper.
"Unfortunately, four people were pulled out from under the rubble dead. The others are still being searched for," the mayor of Glina, Stjepan Kostanjević, confirmed for Croatian Radiotelevision (HRT).
The damage in Glina is immensely large. There is no building that is not damaged. If a new earthquake occurs, the question is whether the remaining buildings can remain intact.
Minstry of internal affairs confirmed six victims and after the seventh was confirmed. ■
Temperatures in parts of Siberia plummeted to minus 50 degrees Celsius (minus 58 degrees Fahrenheit) while blizzards blanketed Moscow in record snowfall and disrupted flights as winter weather swept across Russia.