An apartment building fire sent a column of dark smoke into the Sun Valley sky Thursday, leaving at least two people with serious injuries.

The fire was reported about 11:45 a.m., and firefighters were dispatched to the 7700 block of Lankershim Boulevard to fight the blaze in a four-story, garden-style apartment building, the Los Angeles Fire Department said.

Aerial footage from Sky5 showed that the smoke was emanating from a third-floor unit, though the LAFD later said the blaze was on the second floor, then spread to the third.

More than 80 firefighters were able to extinguish the blaze in just over half an hour, but two people sustained serious burns, the department said.

Firefighters are checking to see if there are any further injuries, and the cause of the blaze is under investigation.