Ankara/IBNS/UNI: As rescue workers rummage through the rubble of collapsed buildings to search for survivors of the deadly earthquake in Turkey and Syria, the toll has crossed 20,000, four days since the natural disaster struck the region, according to official sources.

The magnitude 7.7 and 7.6 earthquakes, centered in Kahramanmaras province, were felt Monday by 13 million people across 10 provinces, including Adana, Adiyaman, Diyarbakir, Gaziantep, Hatay, Kilis, Malatya, Osmaniye and Sanliurfa.

Several countries in the region, including Syria and Lebanon, felt the strong tremors that struck Turkey in the space of fewer than 10 hours, Anadolu news reports.

More than 1,20,344 search and rescue personnel are currently working in the field, according to the Disaster and Emergency Management Presidency (AFAD).

A total of 30,360 people were evacuated from quake-hit regions, AFAD said in a statement.

Speaking in Kilis, Turkish President Recep Tayyip Erdogan said on Thursday that a total of 6,444 buildings had collapsed in the quake zone.

"Last Monday, we were confronted with the worst earthquake this region has ever seen in its history," he added.

Vice President Oktay said while speaking in parliament that "the earthquake affected an area of approximately 110,000 square kilometers (about 42,471 square miles). This is equal to or greater than the area of many countries in Europe.

"This earthquake is the third-largest to occur since the 1668 Great Anatolia earthquake and the 1939 Erzincan earthquake in the last 2,000 years in Anatolian geography."

Turkish Parliament Speaker Mustafa Sentop called on lawmakers on Thursday to make donations worth at least one month's wage to the country's disaster management agency, adding he had donated three monthly wages.

Swiss Seismology Service director Stefan Wiemer told Swiss television channel SRF as quoted by aa.com, "Here is the East Anatolian fault, where tensions accumulate and drain, especially with the 7.7-magnitude earthquake. Such a large earthquake is really rare."

Noting Aleppo witnessing major earthquakes in the past, Wiemer said an earthquake of 7.7 in Turkey is already "major".