Wearing protective suits to avoid being contaminated by hazardous materials, the officers have also put on gas masks.
They started their search of the public toilets yesterday and this morning that search has continued.
The toilets are cordoned off with protective screens.
Sky News’ Lisa Dowd, who is at the scene, said: “This is believed to be one of the areas where Charlie Rowley and Dawn Sturgess visited before they fell ill.
“The forensic intensification at this scene will probably continue throughout the day.”