After the prosecutor's office said it was looking into the cause of the incident, Turkish television stations immediately ended their live broadcasts from the scene. "Twenty-one bodies were pulled out of the rubble including a person of central Asian origin", Soylu said late Saturday.
"In this area, we have faced a very serious problem with illegal businesses like this done to make more money", Erdogan told reporters on his first visit to the site.
However, top three floors of the building were built illegally, the governor added.
The collapse fanned criticism of a government amnesty granted a year ago to people accused of illegal building - a measure announced ahead of municipal elections this March. Istanbul, Turkey's biggest city of more than 15 million people, is also located on a seismic belt.
Friends and relatives waited near the wreckage for news of their missing loved ones as emergency teams, aided by sniffer dogs, worked around the clock to reach possible survivors. A day earlier, a five-year-old girl was rescued from the debris.
The official toll had previously stood at 10 people dead and 13 injured.
Thirty residents were inside the building, which contained 14 apartments, when it collapsed Wednesday, Anadolu said.