Updated

Turkey's state-run news agency says authorities have detained four people in connection with the collapse of an eight-story apartment building in Istanbul that killed 21.

Anadolu Agency said the building's project officer, construction engineer, safety inspector and a technical officer were taken into custody. They face possible charges of negligence.

The building in Istanbul's mostly-residential Kartal district, on the Asian side of the city, collapsed on Feb. 6. Rescuers pulled out 14 other people from the debris with injuries.

Authorities have said the building's top three floors were illegally built.