"The number of our citizens who lost their lives increased to six, with 13 others wounded," Istanbul Governor Ali Yerlikaya said on the scene in the Kartal district on the Asian side of the city, noting another three bodies were found.
The governor later raised the death toll to ten, saying in a one-sentence statement that "four more bodies were found under the rubble."
Earlier in the day, a five-year-old girl was rescued from the rubble 19 hours after the collapse, lifting the number of the wounded to 13.
Yerlikaya said on the scene that the condition of the girl was getting better following a surgery.
Considering the risk of collapse of other buildings on either side of the debris, experts have been monitoring even the "tiniest movements," the governor noted.
"The safety of our friends working on the rubble is also very important for us," Yerlikaya said, adding all the structures within the specific location will soon be technically examined.
The authorities have earlier evacuated a total of seven buildings in the area as a precaution.
Mehmet Gulluoglu, head of the Disaster and Emergency Management Presidency, said it is unclear how many people are being trapped under the debris.
"It is also not possible to say on which floor our teams are working, as the building slipped toward the front before the collapse," Gulluoglu told reporters on the scene.
The rescue operation is continuing despite a cold and wet day.
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