The fire broke out around 2:15 a.m. at the Oak Hill Terrace Apartments on the 1600 block of Oakwood Drive in Lower Merion.
"The entire unit was in flames," said Sarah Sutnick, who woke up to the smell of smoke.
Sutnick said it was difficult to experience a fire especially during a pandemic.
"Especially with coronavirus going on, people are scared, so no one really wants to get close to you, but you've got to help people down those steps and make sure everyone's okay," said Sutnick.
Officials said at least three people have been taken to the hospital with smoke inhalation.
Firefighters had to rescue several residents who were trapped on balconies.
Firefighters said the source of the blaze was in a second-floor apartment.
"There was a lot of stuff in that apartment which made it difficult to enter," said, Chas McGarvey, Lower Merion's fire chief.
Officials said 150 residents in the building's 91 units have been displaced. The Red Cross is working to find them temporary shelter.
In the daylight residents said they're still shaken up.
"You could hear the glass bursting, you could hear people yelling help," said Susan Baron, who added, "You're just left with the anxiety feeling, what's happening now."
Baron said she plans on staying with her daughter in Center City, since she's not allowed to live inside the apartment complex right now, however she hopes to return on Wednesday.
There is no word yet on the cause of the fire.