At least three people were injured in the accident near the United Nations at about 3 p.m.
The FDNY says the driver of the cab was hospitalized with serious head trauma.
His female passenger and the driver of the SUV suffered minor injuries.
A fourth person, a cyclist, narrowly escaped injury as the scaffolding came down.
Rescuers worked to extricate the victims, who were trapped in the wreckage.
The cause of the crash is still under investigation.