Thousands of federal employees in Gatineau were sent home Tuesday after being evacuated from their offices because of a gas leak.

Fire officials say the Freon gas leak started in the building's ventilation system on Tuesday morning, forcing about 4,000 employees out of their offices at Terraces de la Chaudi�re on Eddy Street.

One person reported feeling ill and was treated at the scene by paramedics, according to the city's fire department.

Some of the employees were let back into their offices before midday. Others were sent home for the day.

Government officials say everything will be back to normal on Wednesday.