Police have warned that controlled explosions may be heard as specialist teams continue to work at a flat in Wakefield where 'unknown chemicals' were found.
West Yorkshire Police said this afternoon that searches were continuing at the flat in Westgate End, where a cordon has been in place since Sunday afternoon.
The property became the focus of intense police activity following the arrest of a 41-year-old man on suspicion of drug offences in Leeds earlier that day.
It prompted a search of the flat, with officers finding the chemicals in the process.
They cordoned off an area near Westgate End and a number of homes were evacuated while investigations continued at the scene.
Specialist teams are working there still to make the scene safe for the return of local residents.
The force has advised on Twitter: "Controlled explosions may be heard while any material of concern is safely disposed of by specialist teams."
Officers from the North Easter Counter Terrorist Unit (CTU) have been heading up the investigation.
They charged the arrested man with possession of an offensive weapon under the Explosives Act and two drugs offences.
He was due to appear before Leeds Magistrates' Court earlier today.