Loud bangs were heard in the west London area as police rushed to the scene.
A helicopter has also been circling the area.
A local resident said: “Nice quiet night in Ealing tonight – helicopter circling for the past hour, reported gunshots and our road has been blocked by armed police.”
Sky News has reported that residents have claimed to have heard “gunshot sounds”.
Met Police have said the incident is an ongoing Trident operation.
Trident is the Met Police’s specialist gun crime taskforce.
The Met Police also said there is no risk to the public.
The incident took place on Murray Road in Ealing, London.
People in the area have said armed police can be seen on Murray Road.
One witness said at least eight armed police officers have blocked the road.
People in the area initially thought the noises were fireworks until police arrived.
Reports from witnesses suggest there were at least three “big bangs” heard in the area.
Another witness said police offers are telling residents to stay inside.
One local resident was told to go inside his house by armed police as they searched his garden, according to Sky News.
The Police told Sky News that this was a “pre-planned” arrest.
A police helicopter circled the area overhead for around 30 minutes.
The police have not confirmed yet whether the noises were gunshots.