A gun and two knives were found inside the home of a father-of-three shot dead by police, investigators have confirmed.
Married father-of-three Richard Davies, 41, was fatally shot at his home in St Neots, Cambridgeshire, at 8pm on Wednesday.
Cambridgeshire Police had been called to the house he shared with his wife Samantha and their children in Duck Lane over concerns for people inside the property 15 minutes earlier.
The Independent Police Complaints Commission (IPCC) is investigating the incident, which is the first time an officer has fired a weapon in an operation in the county.
The IPCC has now said early evidence suggests only one shot was fired by the officers who attended.
Mr Davies died from a gunshot wound to the chest, a spokesman added.
A firearm and two knives were found inside the property, which will form part of the investigation.
A statement said: "The IPCC will examine all of the circumstances surrounding the shooting.
"House-to-house enquiries have been undertaken and witness statements will be taken over the coming days. Cordons remain in place in Duck Lane at this stage while the investigation continues."
Guido Liguori, IPCC Associate Commissioner, said: "I would like to send my condolences to Mr Davies' family and friends at this difficult time.
"It is essential when the police use lethal force that there is a thorough and independent investigation of that decision, and I would like to assure all those concerned that we will investigate the full circumstances surrounding this incident."
Mr Davies, a hydraulic fitter, was described as a friendly family man by neighbours. It is understood he had been absent from work in recent weeks.
His mother Gill Davies wrote on Facebook: "God only knows how things came to this so to those who are speculating, please keep out of it.
"If you do not know please don't just make it up.
"Richard was loved and respected by a lot of people, family and friends alike.
"He and Sam also had three wonderful children who don't need all this nonsense."
Mr Davies worked for mechanical engineering firm Bosch Rexroth in nearby Cromwell Road.
A spokesman said: "Bosch Rexroth is saddened by this news.
"As this is an ongoing investigation, Bosch Rexroth will make no further comment at this time."
Residents reported hearing raised voices shortly before the police arrived.
Neighbours described hearing two or three loud bangs, which they initially thought were fireworks or television sound effects.