Dissident republicans have been blamed for a series of arson attacks which destroyed several major retail premises in Newry overnight.
Homes were evacuated as fire swept through Carpetright and MFI stores in the city's Damolly Park area.
At the same time a JJB sports shop was gutted in a blaze a mile away on Merchants Quay. A nearby TK Maxx store suffered heat damage. Other stores including B&Q, Land of Leather, Currys, Harveys Furniture and Dunnes Stores suffered lesser damage.
Nearly 150 firefighters and 26 appliances were brought in during the emergency.
Fire fighters believe the fires may have been started by incendiary devices planted before the shops closed last night.
Police urged all businesses and keyholders in the city to check their premises. They were also examining a security alert on the Newry railway line near Cloughoge Bridge.
As the blazes were brought under control Group Commander Walter Johnston confirmed they were probably started deliberately by fire bombs. He said incendiary devices may have been planted in the shops before closing yesterday.
"It would be most unusual to have this type of incident at the same time involving four premises," he said.
"As soon as the buildings cool down we will be going through them and police will be helping us. We are almost certain they were malicious fires, but how they actually started we are not sure yet.
"The buildings were totally secure when the fire crews arrived."
Ulster Unionist MLA Danny Kennedy said: "People are completely appalled, shocked and stunned. Undoubtedly it was caused by republican dissidents, and it may well be linked to the anniversary of internment.
"These are multi-national businesses and its important everything possible is done to make them stay in Newry."
Davy Hyland of Sinn Féin said the attacks looked like the work of dissident republicans.
He added: "There is very, very little if any support for what happened. Newry has been through difficult times, but in recent years its gone through a resurgence. Jobs are now in danger of being lost."
The SDLP in Newry claimed up to 60 jobs could be lost because of the destruction.
Dominic Bradley MLA said: "This type of wanton destruction of property and jobs only underlines once again the utter futility of violence."
The Mayor of Newry and Mourne Michael Carr said there was a tremendous sense of shock and disbelief in the city. "The people of the city thought that we had put this type of thing behind us," the mayor said.
"It is clear that no cause can justify this type of destructive and futile action," he added.