Could it have been a member of cabin crew who made the 'emergency, emergency' call ha
Unlikely. If the flight deck crew were incapacitated then the cabin crew would have been too. They were at TOC - the cabin crew would already be standing and moving about the cabin, probably with the carts. This involves physical activity. The flight deck crew remain seated. What I'm saying is the cabin crew would probably have succumbed to incapacitation first.