Two people were rescued from a fire in an unoccupied apartment in Potrero Hill Wednesday morning with serious injuries, according to fire officials.

The fire in a three-story building in the 1100 block of Connecticut Street was reported around 8:10 a.m., according to Battalion Chief Michael Thompson.

When firefighters arrived on the scene, one adult was already being rescued from the building by construction workers. Firefighters located a second person on the second floor a few minutes later.

Both victims, a man and a woman, were transported to local hospitals with heavy smoke inhalation injuries in critical condition.

Firefighters were able to put to put out the fire, which appears to have started in the first floor living room of an unoccupied unit, Thompson said. The cause is under investigation.

#010219WF1 UPDATE FIRE UNDER CONTROL 1 critical victim rescued by construction workers 2nd critical victim located on 2nd floor and rescued by #yoursffd Fire under investigation https://t.co/4LePCJ5W2A

— San Francisco Fire (@sffdpio) January 2, 2019