British counterterror police have shot a woman and arrested six people in raids in London and southeastern England. A senior officer said Friday the arrests disrupted an active terrorist plot.

The woman in her 20s is in serious but stable condition in a hospital after the raid on a house in Willesden, northwest London, the Metropolitan Police said Friday.

In footage shot by a witness, what sounds like several shots ring out as police surround the row house on Thursday evening.

Police said the injured woman was the subject of an ongoing investigation. She is under police guard but has not been arrested.

A 20 year old woman and a 16-year-old boy were arrested at that address, as was a 20-year-old man nearby. A man and a woman both aged 28 were arrested when they returned to the house later.

A 43-year-old woman in Kent county, south of London, was also arrested.

Police say the suspects are being held on suspicion of preparation of terrorist acts.

A police statement says the raids were not related to Thursday's incident near Parliament in which a man was arrested while allegedly carrying large knives in a backpack.

Metropolitan Police Deputy Assistant Commissioner Neil Basu said the Willesden raid disrupted an "ongoing" plot, but did not elaborate.

Basu said that in both the Willesden and Parliament incidents, "we have contained the threat that they posed."

Britain's official threat level from international terrorism stands at the second-highest, "severe," meaning an attack is highly likely.