Neighbours in a quiet residential street where two men died have told how they were awoken by screams.
A 28-year-old woman was Tasered and arrested on suspicion of murder after the incident in Ilford, east London, on Sunday morning, said the Metropolitan Police.
The men, believed to be in their 40s, were found seriously injured at the property in Tavistock Gardens and died at the scene, the force added.
Police, who were called to a reported disturbance shortly before 4.30am, believe they know the victims’ identities and are trying to contact their relatives.
The woman, who had non life-threatening injuries, was taken to hospital for treatment and is now in police custody.
Police set up a wide cordon around the area and several forensics officers have been seen outside the house.
Neighbour Inamul Hussain, 32, told reporters he called police after hearing a woman screaming.
He said: “I saw them Taser her, she had blood on her. I heard police say ‘put the knife down’.
“She was screaming something about her husband but it was quite broken, I think they’re Polish.
“Several men and several woman live there, they are always partying and drinking.”
Mr Hussain took a video of several police outside the house, during which officers can be heard shouting “show me your hands now” and “come here now” and “get out, get on the floor now”.
A man who lives a short way down the street told the PA news agency he woke to the sounds of a woman screaming.
Kuddus Miah said: “She was screaming ‘Help, help, call the police’.
“The police and ambulances were there very quick.”
The 44-year-old said a neighbour told him they saw a woman who was “coming in and out of the house, crying out for help, and apparently had a knife in her hand”.
Mr Miah said he thought those involved in the incident were new tenants, adding: “We’ve lived here around 15 years and it’s a very quiet neighbourhood, it’s shocking.”
Another man, who gave his name only as Singh, described how a woman he saw was “quite hysterical, calling for the police, screaming”.
He added: “She was at the doorstep then went back inside and then out again, screaming and screaming for help.”
Murder detectives continue to probe the incident.