The Kamov KA-52 went down when the ejection seats malfunctioned, sending the chopper crashing into a concrete barrier. The pilots were described as "in shock, but conscious."
"Doctors have assessed their condition as serious, but they believe there is a chance they will be saved," said a spokeswoman for city health services.
Investigators said they had collected technical documents and the in-flight recorder to determine what caused the crash, the second of a Kamov KA-52 in two years.
In March 2012, two pilots were killed when their helicopter crashed during a training exercise.
The Kamov KA-50 and KA-52s have ejection seats that operate after explosives blow off the chopper's rotor blades, allowing the crew to be safely ejected.