01/24/2013 14:01 EST | Updated 03/26/2013 05:12 EDT

2nd suspected case of workplace carbon monoxide poisoning in N.B.

Safety officials in New Brunswick are investigating another suspected case of carbon monoxide poisoning at a workplace in the province.

Fourteen employees working in a potato warehouse in New Denmark fell ill on Wednesday afternoon, WorkSafeNB officials confirmed on Thursday.

"They appeared to be exhibiting signs of dizziness and one person may have lost consciousness, so they called for emergency assistance," said Richard Blais, who is part of the WorkSafeNB investigative team.

Investigators believe the workers, who were racking potatoes at the time, were exposed to carbon monoxide fumes.

At least 11 of the workers were treated at the Grand Falls General Hospital or the Hotel-Dieu of St. Joseph Hospital in Perth-Andover, said Blais . It's not yet known whether they have all been released.

Investigators are still trying to determine the source of the fumes, but say they may have come from a lift truck.

"We're tying to piece together what could have been the cause," Blais said.

The warehouse, which was being rented by a numbered company, will remain closed until the source of the gas is found.

Miramichi case deemed carbon monoxide

Meanwhile, safety officials continue to investigate a similar incident at Sunny Corner Enterprises Inc. in Miramichi, which sent at least 34 people to hospital on Wednesday morning.

WorkSafeNB officials have determined it was carbon monoxide poisoning, but are still trying to pinpoint the cause, spokesman Fidele Cormier told CBC News on Thursday.

"They're looking at various potential sources, taking measurements of air quality carbon monoxide, whether there were any rolling vehicles, any types of furnaces and so on," Cormier said.

"It's very cold so furnaces, for example, will run hotter than they normally do. There was shortage of propane in one of the tanks, so that may be. There are several potential causes, but we're not down to the exact cause at this time."

Three inspectors were on site, said Cormier.

"There's also other people from private industry called in to test equipment to see if there are any faults for the heating system and so on."

The employees, who were assembling drill rig components at the northern manufacturing plant, were also complaining of headaches and nausea, like the New Denmark case, as well as respiratory issues and confusion. One of them passed out.

All of the employees have since recovered and been released from hospital.

Firefighters vented the building by opening the windows and bay doors.

General manager George MacLeod says levels at the plant are back to normal and there is no sign of further contamination.

But the building remains closed on Thursday while officials try to determine the cause and origin of the leak.