A man was rushed to a major trauma hospital after being struck on the head by an object while in a lift shaft at a Plumstead building site on Wednesday.
The incident happened at a construction site for flats on Plumstead Road, sparking a sizeable emergency services response and air ambulance call out.
The man's injuries are not thought to be life-threatening, a Met Police spokesperson said.
The lift shaft was sealed after a request from the health and safety watchdog, the HSE, to prevent further injuries.
The incident lasted around an hour.
A London Ambulance Service spokesperson said: "We were called at 8.51am this morning to reports of an incident at the junction of Plumstead Road and Villas Road, Plumstead.
"We sent resources to the scene, including ambulance crews, members of our Hazardous Area Response Team (HART), an incident response officer and London's Air Ambulance.
"The first of our crews arrived in five minutes. Our crews treated a man at the scene, before taking him to a London major trauma centre."
Firefighters said they were called to the scene to assist police and paramedics.
"Crews worked to support emergency service partners and make the scene safe," a spokesperson said.
The Brigade sent two fire engines and two Fire Rescue Units from East Greenwich, Lewisham and East Ham fire stations to the scene, declaring the incident over by 9.52am.
According to plans submitted to Greenwich Council, the construction is for a mixed use development for 294 new homes and a new "state of the art" building for Greenwich College which will have five storeys.
The incident is understood to have occurred at a plot earmarked for the new homes under developer L&Q.