EIGHTEEN people are being treated after toxic gas used to kill rodents escaped from a ship docked at a harbour in Northern Ireland.
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.
Gardai have been informed of the potential of the chemical compound to drift into their area but fears that it may spread into Louth have lessened, and a crisis management team there has been stood down.
A Police Service of Northern Ireland (PSNI) spokesman said: "It is believed that there are five casualties suffering from the effects of exposure to the gas."
But a Northern Ireland Ambulance Service 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 Northern Ireland Fire and Rescue Service spokeswoman confirmed they were dealing with a major incident.
Sinn Fein Warrenpoint councillor Michael Ruane said a specialist large ambulance service truck was parked near the incident.
Emergency services have gathered in the main square and the town hall has been made available if people have to be evacuated.
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 major emergency has developed, with response teams working together.
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."
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.
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.
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.
It is understood the MV Arklow Meadow was carrying a pesticide grain treated with the noxious chemical and used to control vermin, which became wet and released gas.
It is owned by Arklow Shipping, which is based in Arklow on Ireland's east coast, south of Dublin in Co Wicklow.
According to the company's website, the vessel was built in South Korea in 2010. It has been strengthened for carrying heavy cargo and registered in Arklow. The company also has offices in Holland.
A member of staff at the company, who did not identify himself, said the incident had been "blown out of all proportion".
Police said all residents who left their homes have been allowed to return; however, they are advised to continue to keep doors and windows closed.
A fire service spokeswoman said: "The Public Health Agency (PHA) has advised that all risk of adverse health effects associated with this incident applies only to those who have come into direct contact with the gas.
"The emergency services are currently identifying and treating all such individuals.
"The PHA would emphasise that there is no risk to the wider public, but asks that people in the general area co-operate with the authorities to ensure that this incident is handled safely and effectively."