Eighteen people are being treated after toxic gas used to kill rodents escaped from a ship docked at a harbour in the North.
Cargo on the vessel at Warrenpoint, Co Down, had become wet and unstable and a 50m cordon has been set up.
The gas is aluminium phosphide, a pesticide used to kill small mammals such as moles and rodents.
A Northern Ireland Fire and Rescue Service spokeswoman said that they were dealing with a major incident.
The spokesman said: "We have 18 patients. It is a chemical incident on a ship. Nine are en route to Daisy Hill Hospital and nine are at the scene and they will be transferred to Craigavon Area Hospital."
A Maritime and Coastguard Agency spokesman confirmed the boat involved was called the MV Arklow Meadow.
The incident was reported to the ambulance service at 9.47am.
The ambulance service said 15 of its vehicles have been deployed: five accident and emergency ambulances, three hazardous area response teams, one paramedic rapid response vehicle, five ambulance officers, a doctor and an emergency equipment vehicle.
Emergency services have gathered in the main square and the town hall has been made available if people have to be evacuated.
Sinn Féin Warrenpoint councillor Michael Ruane said a specialist large ambulance service truck was parked near the incident.
Mr Ruane said: "The incident is confined to the harbour at this moment in time. The fire service and police seem to be keeping well back from it.
"There are a number of boats in the harbour - there are a number of small mussel boats and some larger vessels."
A PSNI spokesman said: "The cordon has been extended and a number of homes have been evacuated from Newry Street to the square.
"The ship is being held within this cordon. The Town Hall has been made available for those evacuated.
"Police are advising nearby residents to close all windows and doors.
"Due to the north-east wind blowing at present, residents in Omeath and Carlingford (across Carlingford Lough in the Irish Republic) are also being advised to close all windows and doors."
Aluminium phosphide (AIP) gas is used as a pesticide, insecticide, and fumigant for stored cereal grains.
It is used to kill small mammals such as moles and rodents.
AIP is also used industrially.