A woman who was being held "hostage" according to witnesses has died following serious injuries sustained from the incident.
The 36-year-old woman died in a London hospital on 8 May from injuries believed to have been caused by a handgun.
The incident that led to her death is now being treated as murder and an investigation is under way.
Two days before her death (6 May), officers had attended a property in Dartford, Kent, following reports of a "disturbance".
Police forces accompanied by a trained negotiator attempted to engage with a man inside the property.
After an hour-long stand-off, neighbours heard what they described as sounding like two rounds of gunshots.
The man, 29, was taken to hospital with a serious firearm injury and is in critical condition. He is also the suspect in the murder investigation.
Witnesses who lived nearby said the woman had been "held hostage" by a man at the back of the property.