A man shot dead by police in Meir, Stoke-on-Trent, was seen with a sword and firearm, the Independent Police Complaints Commission (IPCC) has said.
Police remove the body from the house in Bondfield Way
A spokesman said police were called to flats in Bondfield Way by the 47-year-old victim, named as Philip Marsden, after midnight on Monday.
They left but were later called back by a neighbour reporting a disturbance.
An armed response unit was called after the man was seen with the weapons. He was shot a short time later.
The man was shot at 0121 GMT, 11 minutes after the armed unit was called.
Staffordshire Police say no other member of the public was involved and no-one else was injured.
A team of IPCC investigators, led by senior investigator Malcolm Niblo, worked through the night at the scene with officers from Staffordshire Police's professional standards department carrying out an assessment.
John Crawley, IPCC commissioner for the West Midlands, said: "The IPCC will investigate all the circumstances leading to the use of armed officers for this operation together with the circumstances leading up to the shooting.
"We are working with investigators from Staffordshire Police to arrange an early and smooth handover of the investigation and I am satisfied that we are receiving their full cooperation.
"The IPCC will ensure that a thorough but timely investigation is carried out to reassure the man's family, the officers involved in the operation and the public."
Mr Crawley is appealing for any witnesses to contact the IPCC. He added: "We are particularly interested in any video footage, including mobile phone footage, that anyone may have."