The quake occured at 20:55 local time, Kandilli Observatory announced.
Turkish Interior Minister Suleyman Soylu earlier told reporters that four people had lost their lives in the earthquake, and 10 buildings had been damaged in central Elazig.
Turkish Minister of Health Fahrettin Koca said 13 people in total lost their lives in Elazig and another five in Malatya, with two people dying of heart attacks.
On top of the 18 people who lost their lives in the two provinces, the earthquake injured 405 people in Elazig and 148 in Malatya.
Some 100 buildings collapsed in the neighbouring Malatya province, and there are animals trapped in the rubble, Malatya’s Mayor Mikail Suluk said.
Turkey’s Disaster and Emergency Management Authority (AFAD) urged people to stay away from damaged buildings, and keep roads clear for emergency rescue units.
Schools in Elazig and Malatya will also have their doors open, as announced by Turkish Education Minister Ziya Selcuk.
The rescue mission continues with food trucks, tents and blankets dispatched from all corners of Turkey to the people who are spending the night outside, as aftershocks continue.
Istanbul has dispatched 300 firefighters and rescue officers.
There have been 97 aftershocks recorded. Five out of the 553 injured people remain in critical condition.
Reporter's code: 50101