Most people are being let back into their units after a fire in a central Ottawa apartment building Saturday morning, which was apparently caused by a medical oxygen supply.

Ottawa Fire Services said they were called to 345 Lebreton St. S. just after 4:45 a.m. Saturday after a report of a fire at a second-floor unit.

si-ott-lebreton-apr20

Fire crews respond to a blaze on Lebreton Street South, near Dow's Lake on Saturday. (Photo courtesy of Ottawa Fire Chief John de Hooge)

Ottawa paramedics said they treated one man and three women for smoke inhalation, including a pregnant woman who was also experiencing abdominal pain.

They said they originally took in 20 evacuated residents in their treatment bus until an OC Transpo bus arrived to take them in. They later said all but three were able to return to their apartments, the exceptions a result of of smoke damage.

The man who lived in the unit where the fire started will not be able to return, as it was "completely gutted," according to fire officials.

The Canadian Red Cross also helped care for the tenants.

Damage is estimated at $375,000 and for officials said the cause is suspected to be an open flame getting too close to a medical oxygen supply.

Lebreton Street South was closed between Carling Avenue and Daniel McCann Street because of the fire, but was open again as of noon Saturday.