An investigation has been launched into the cause of a leak which saw more than 150 people treated by paramedics at HM Inland Revenue in Central Milton Keynes yesterday.
Staff working in the Inland Revenue building reported a strange smell at around 1.30pm on Wednesday, and a number of people developed breathing difficulties. The building was evacuated and a cordon was put in place around it.
Decontamination tents were set up as well as shelters for workers who were being seen to by paramedics.
Many others were told to stay in their surrounding buildings, but be prepared for a quick evacuation.
Paramedics from South Central Ambulance Service treated and discharged 27 people and triaged and discharged a further 126 people. No-one was taken to hospital.
Firefighters from across the region wearing breathing apparatus entered the four-storey ~Bowback House and isolated the air conditioning and refrigeration.
A search late in the afternoon found no trace of any harmful substances, and the air conditioning was reactivated at 7.45pm for further tests to be carried out.
Thames Valley Police and Buckinghamshire Fire & Rescue Service are investigating the cause of the incident, though there is nothing to suggest it is suspicious.
Control of Bowback House was handed back to the facilities manager at around 9pm last night after a gas leak caused a huge evacuation in Silbury Boulevard.
Employees have been given the day off after the events yesterday.