Turkish officials say one more person has been found dead in the rubble of a collapsed eight-story building in Istanbul, raising the death toll to at least three.

Istanbul Governor Ali Yerlikaya told reporters early on Thursday that rescue teams working overnight pulled 12 people out of the rubble with injuries. Three of them were in serious condition, Yerlikaya said.

It was not immediately clear how many people were still trapped in the debris of the building on the Asian side of Istanbul in the mostly residential Kartal district.

The building, with 43 people living in 14 apartments, collapsed on Wednesday. The cause was under investigation but authorities said the top three floors had been illegally built.