ABC News' Katti Gray reports:

A Navy construction crew passing by the scene of a horrific wreck joined forces with emergency rescue workers to keep a mangled BMW carrying a California mother, her 10-year-old daughter and 10-week baby from slipping off a bridge and plunging into a 100-foot deep ravine.

The vehicle dangled off the bridge Thursday after being rear-ended by a tractor-trailer, which broke through the concrete barriers and fell into the creek bed. The truck driver was killed.

Santa Barbara County, Calif., Fire Department rescue workers had been trying to pry Kelli Lynne Groves and her children out the car when the Navy Seabees were driving by with their equipment.

"They all got out and wanted to know if they could help maybe with traffic or something else," California Highway Patrol Officer Danny Maher said. "They had a large forklift with them. … It was actually just good luck on our part."

The forklift held the car steady until the county workers were finally able to free the family. The three were airlifted to Santa Barbara's Cottage Hospital where the baby girl, who had been in a car seat, was treated for minor injuries.

"I think that car seat saved her life," Maher said.

Sage Grove, 10, was upgraded from critical to serious today and the girl's mother was listed in fair condition today, a hospital nursing supervisor told ABC News.