Heavy equipment arrived to dismantle the wreckage and the rescue operation was expected to continue throughout the night.
Television channels showed a truck parked nearby that had been crushed by a wall of debris.
Azerbaijan's ANS television quoted a source in the prosecutor's office as saying 22 people were in the building when it went down, but at least seven of them had been rescued.
In a conflicting account, an emergencies service spokesman said that contractors believed four or five people could still be trapped under the rubble.
The capital of Azerbaijan, an oil-producing ex-Soviet republic, is in the middle of a construction boom with high-rise buildings going up across the city which lies on the shore of the Caspian Sea.