Armed police carried out an early hours raid at a house in Leeds as part of an investigation into firearms offences.
Officers entered the property at Arthington Place in Hunslet at 2.30am on Monday and arrested three men and a woman.
West Yorkshire Police said an "armed containment" was put in place while the property was searched for other suspects. A cordon was also established around the surrounding area while the operation took place.
At about 12.20pm another male was detained within the premises and arrested.
Officers also searched an address in Whitfield Square, Hunslet, as part of the operation, which is connected to an aggravated burglary at Low Lane in Clayton, Bradford, on 21 February.
Three people were arrested at the time after a firearm was discharged towards a vehicle.