The fall was reported at 7:30 a.m. at the Twin Creek Apartments at 1111 James Donlan Blvd.
Danielle McFarland, her mother in law and 8-year-old daughter were looking at the vacant unit when a wooden railing gave way. They were transported to a local hospital for observations and had minor injuries.
All three plunged about 15 feet from the second-story balcony and landed on a grassy area. Paramedics treated the family on the ground and the older woman was flown by CALSTAR helicopter to Walnut Creek's John Muir Hospital.
McFarland and her daughter were taken by ambulance.
"I was scared to death that it was going to be worse," McFarland's friend Audrey Lambert said. "They are doing pretty good, considering. Just came back from the hospital and they were given medication, pain medication. They are resting comfortably at this point."
Antioch building inspector Ryan Graham says the broken railing and nearby stairway were both compromised by dry rot, something some residents had complained about often.
"There is some evidence of dry rot in the area and that's what we're looking for in the rest of the complex," he said.
City inspectors went to each building in the 30-year-old complex. They ordered Twin Creeks management to immediately relocate tenants in three apartments.
"We found one other building that specifically concerns us; that we're going to be addressing with the management that we want immediate attention to," Graham said.
Other residents received notices from building management, warning them to stay off their balconies until they can be further examined.
Twin Creeks tenant Steve Elasdell lives in an upstairs unit with his family, including a young daughter.
"I'm not leaning on any rail. I'm going to be very careful with the little one too," he said.
Rico Thomas has lived there just a few months. He's been pleased with the condition of the apartments until now.
"It bugs me a lot. I'm thinking about really moving, to tell you the truth," he said.
City inspectors said dry rot inspections are not part of the routine. Once a building is completed, it is up to the owner to perform the proper maintenance and repairs over the years, to ensure that something like Thursday's fall doesn't happen.