Firefighters were today maintaining a 200 metre evacuation zone around a Co Armagh chemical factory because of fears of gas cylinders exploding.
More than 30 firefighters using specialist equipment put out the blaze at the plant in Lurgan last night but the area remained sealed off as a precaution.
The fire began at the plant in Watson's Lane in Lurgan at around 7.30 p.m.
Police closed the town centre to traffic and evacuated houses and other buildings within a 400 metre zone.
Divisional Officer Ken Leathem of the Fire Service of Northern Ireland confirmed that the exclusion zone was reduced after the
blaze was put out.
"The fire itself is now under control but with acetylene we have to keep them under observation for 24 hours.
"If they are subjected to heat they could start to decompose inside and this could cause an explosion."
Mr Leathem said the fire was in an unoccupied storeroom. A small amount of chemicals, believed to be phosphorous and magnesium were involved.
Six fire appliances and three special appliances attended the scene last night. The cause of the fire was still being investigated.