A man was arrested last night after an incident which saw hundreds of residents evacuated from their homes in Trowbridge.
Emergency services were first notified of a fire and smoke in the kitchen of a first floor flat of a house on the corner of Bond Street and Wesley Road at 5pm.
Two fire crews attended the unoccupied flat and nearby residents were immediately evacuated, with Bond Street later being sealed off in both directions.
As investigations continued, the incident was scaled up to what police described as a 'major incident' at 6.30pm, and police extended the cordon to within 100 metres of the premises.
It was believed chemicals had been found and Ministry of Defence experts were called in, with one fire crew remaining on the scene to assist the police investigation.
A spokesman for Wiltshire Fire and Rescue service confirmed the cause of the fire was linked to the suspected chemicals found at the scene, saying: "In the process of putting out the kitchen fire we became aware of items of concern, for which we handed things over to the police.
"The cause of the fire was tied up with the items of concern."
A 27-year-old was later arrested in connection with this incident and is currently in custody at Melksham Police Station. Enquiries are on-going.
Detective Inspector Ben Mant at Wiltshire Police said: "Firstly, I would like to thank the local community for assisting Wilshire Police this evening.
" I would like to extend my thanks to local people for their patience and co-operation."
Anyone with information is asked to call Wiltshire Police on 101 or Crimestoppers on 0800 111 555 where information can be left anonymously.
The alarm was raised by Amadou Gillan, who lives in the flat above the fire. He said: “I was upstairs and I could smell the fire.
“I went downstairs and could see the smoke inside, and my neighbour, who was in the next flat.
“She was holding a garden hosepipe. She gave it to me and I knew I couldn’t put it out, and we just got out of there.”
Neighbour Julie Coombs also witnessed the fire. She said: “About lunchtime I could smell something like tar burning. I thought nothing of it, then it just got stronger, and I went outside and it was billowing out the back.
“I’ve seen the firefighters coming in and out with breathing apparatus. It was a horrendous smell.”
Hundreds of residents were evacuated, and gathered at the edge of the cordon, sharing cups of tea with the police officers manning the lines.
While Wiltshire Council was looking into the possibility of setting up a refuge centre at the Clarendon Sports Hall bomb disposal experts entered the flat, and the cordon was lifted around 8.40pm.