Forensic examination of the home of a man shot dead by police after a seven-hour siege was delayed over fears it may contain explosives.
The Independent Police Complaints Commission (IPCC) said specialist teams had to be drafted in to search Alistair Bell's house in Kirkheaton on Tuesday.
Mr Bell, 42, died after a night-long standoff. His home has now been declared safe.
The siege began after an officer who went to arrest Mr Bell was shot.
It has since emerged that the 29-year-old West Yorkshire Police officer was saved from serious injury by his body armour.
The IPCC started an investigation into the incident after it was referred to them by the force.
In a statement, the police watchdog said: "IPCC investigators were unable to enter the house to begin their examination on Tuesday due to fears it may contain an improvised explosive device.
"The property has been declared safe now following a search by specialist teams and a forensic examination is being undertaken."
The IPCC added that a 9mm self-loading pistol had been recovered from the house.
The siege, which resulted in armed police surrounding Mr Bell's home, took place in Cockley Hill Lane, near the centre of Kirkheaton.
The IPCC said West Yorkshire Police had received a 999 call at about 1800 GMT on Monday, alleging that Mr Bell had made threats towards a woman and her husband.
Police officers visited the woman and then went to Mr Bell's home at about 2200 GMT.
"It is understood Mr Bell produced a weapon and fired at the unarmed officers," the IPCC said.
"One bullet struck the body armour of one of the officers and he sustained bruising to his lower back."
Firearms officers were deployed and negotiations began with Mr Bell.
However, at 0530 GMT on Tuesday, Mr Bell died after an officer fired a Heckler and Koch G36 carbine weapon.
A post-mortem examination was carried out on Tuesday evening. Police said Mr Bell's next of kin had been notified.