ANKARA 

A powerful earthquake struck the Turkish metropolis Istanbul on Thursday, according to Turkey's Disaster and Emergency Management Authority (AFAD). 

AFAD said a 5.8-magnitude earthquake centered in the Sea of Marmara hit at 1.59 p.m. (1059GMT). 

"Eight people were slightly injured in the earthquake," President Recep Tayyip Erdogan told reporters at Istanbul’s Ataturk Airport returning from his visit to the UN General Assembly in New York. 

"According to AFAD, the magnitude of the earthquake is 5.8 and 28 aftershocks are recorded so far," Erdogan said. 

The earthquake, off Silivri district, occurred at a depth of 6.99 kilometers (4.3 miles), some 22 km (13.6 mi) from Silivri. 

The region was also shaken by aftershocks. 

A 3.6-magnitude earthquake also shook Istanbul earlier today, at 10.32 a.m. (0732GMT), said AFAD. The epicenter of the quake was the Sea of Marmara.

On Tuesday, a 4.6-magnitude earthquake also hit off Silivri, according to AFAD.

In addition to Istanbul, Turkey's most populous city, the earthquake was also felt in nearby urban areas such as Kocaeli, Sakarya, Yalova, Tekirdag, Edirne, Manisa and Kirklareli.

Kocaeli Governor Huseyin Aksoy and AFAD officials in Sakarya told Anadolu Agency that no negative outcome of the quake has been reported so far.

The Istanbul Governorship said primary and secondary schools have been temporarily closed on Thursday due to the quake.

Bursa Governorship announced all schools were closed on Thursday in the province due to the anxiety that came after the quake, according to the provincial directorate for national education.

Yalova Governorship also decided on a one-day closure of all schools in Thursday afternoon, Ali Tosun, provincial director of national education, told Anadolu Agency. 

Our biggest consolation is that there is not any loss of life due to the quake, Turkey’s Health Minister Fahrettin Koca said on Twitter. 

Koca added that the Health Ministry is on alert for all kinds of disasters. 

Youth and Sports Minister Mehmet Kasapoglu and Justice Minister Abdulhamit Gul conveyed good wishes to everyone who were affected by the quake.

A minaret of a mosque in Avcilar district in Istanbul fell due to the quake.

According to AFAD, two buildings were damaged in Sultangazi and Eyup districts while residents of a building which leaned aside due to the earthquake were evacuated in Sirinevler district of Istanbul.

Istanbul Mayor Ekrem Imamoglu said he was happy that there is not any loss of life or crucial injury according to initial reports. 

Aftershocks could create an energy which will break the earth’s crust, Kerem Kinik, Turkish Red Crescent head, said on Twitter.

Kinik urged citizens to leave their houses which were damaged and risky to stay in. The buildings established before 1999 face a risk of demolition, he warned.

Turkish Vice President Fuat Oktay said the schools, which were closed on Thursday following the quake, will be opened on Friday as there is no need for closure as per evaluations. 

"Our schools will remain open on Friday. We are expecting our students will attend schools tomorrow," Oktay told reporters at a news conference in Istanbul.

* Iclal Rabia Turan and Burak Bir contributed to this story