Three fatal fires over the weekend were accidental and connected to an overload of sockets and electrical issues, the fire service has said.
They issued a public safety warning, describing the number of recent incidents as highly unusual and alarming.
On Friday two people died in house fires in Bangor, County Down and north Belfast. On Saturday a woman died following a fire at a house in west Belfast.
There was another serious house fire in Lisburn on Sunday.
Area Commander Suzanne Fleming said: “Our thoughts and sympathies are with the family members and loved ones of the people that have lost their lives.
“It is very unusual to have this many house fires over a weekend and it’s certainly not something the public would be used to either in Northern Ireland.”
The fire service are urging the public to make sure they do not overload electrical sockets, they have working smoke alarms at their properties and they have a fire escape plan in place.