Lorna Murphy, Transport for London’s (TfL) director of buses, said her thoughts were with those injured in the crash.
“We care deeply about the safety of everyone who uses or works on our transport network,” she said.
“Safety is our top priority and we are working with the police and the operator, Go Ahead London, to establish what happened.
“This must have been a distressing incident for everyone involved and we have support available for anyone affected.”
The crash involved a route 35 bus that collided into a route 333 that was not in service, TfL confirmed.