The police, ambulance, coast guard and fire service have all been scouring the water near the Woolwich Ferry since around 1.15pm today (March 31).
The girl is thought to have entered the river near Barge House Causeway near Royal Victoria Gardens.
Residents in Woolwich have reported seeing coastguard and police helicopters searching the Thames in the area.
One helicopter has been panning up and down the river in Woolwich area according to flight tracking data.
Meanwhile, shipping data shows fire, ambulance and police boats in the same area of the Thames.
Meanwhile, the fire service has deployed a drone as part of a “systematic search of the area”, along with crews from East Ham, Barking, Ilford and Bexley fire stations.
A Metropolitan Police spokesperson said: “Police were called at around 13:15hrs on Monday, 31 March to reports of an 11-year-old girl who had entered the River Thames near to Barge House Causeway, E16.
“A large scale response is ongoing, supported by all emergency services, working together to conduct an extensive search in efforts to locate her.
“Her next of kin have been made aware and are being supported by officers.”
A London Ambulance Service spokesperson said: “We were called at 1.19pm today (31 March) to reports of a person in the water at Lowestoft Mews, E16.
“We have sent resources to the scene, including an ambulance crew, an advanced paramedic, an incident response officer and members of our hazardous area response team (HART).
“The incident is ongoing and we are working with our emergency services partners.”
