The incident has been referred to the Health and Safety Executive.
A London Ambulance Service spokeswoman said: "We were called at 1.39pm to Pembury Road at the junction with Dalston Lane to reports of a collapsed advertising board.
Accident: police at the scene in Pembury Road (Picture: Twitter/@daverholland)
"We sent a duty officer to the scene, two ambulance crews and a single responder in a car. We treated two patients; a woman reported to be in her 30s for leg and back injuries and a man reported to be in his 30s for a wrist and hand injury. They were both taken to Homerton Hospital - the woman was taken as a priority."
Hackney Council declined to comment.
In a tweet, it said: "A104 Pembury Road closed from Pembury Junction due to building works incident. Amhurst Road and Dalston Lane open but congested."
A spokeswoman for Bellway Homes said: "As a matter of priority, we are working with our principal contractor Ardmore Construction to investigate the incident. Our thoughts are with the injured parties, who we wish a speedy recovery.”
