Witnesses said that dozens of police, ambulance and fire vehicles can be seen in the area, close to an industrial estate in Park Royal.
A number of roads and pathways have been cordoned off, with police continuing to extend the area. Officers have told people the cordons could be in place for "hours".
Emergency staff wearing diving clothing, such as wetsuits, could also be seen walking close to where the incident took place.
The body of a newborn baby has been found in the Grand Union Canal in north-west London.
The Metropolitan Police said officers and paramedics were called at just before 1.20pm on Sunday to the body of an infant found in the water near to Old Oak Lane. The baby was pronounced dead at the scene.
An investigation is under way to establish the circumstances, the force said. A number of cordons are in place at the scene.
The Met has urged the baby's mother to "seek medical assistance" by dialling 999.