When the family, which included a father and his 8-year-old son and 4-year-old and 6-month-old daughters, backed their car out of the driveway, they hit a sinkhole that had been hidden by overflowing water.
The father, identified by The Associated Press as Darwin Mendoza, said the family escaped the car and watched as the sinkhole grew.
Other families in the neighborhood were rushed out of their homes after the break in the 12-inch main caused water to spill everywhere.
"The cars have been pulled out of the sinkhole and we are in the process of repairing the broken pipe," Washington Suburban Sanitary Commission spokeswoman Lyn Riggins told ABC News.
Nearly 80 homes and businesses in the area were without water but should have water restored by tonight, according to Riggins.
The commission has responded to 400 water main breaks in the area this month alone, according to Riggins. There are normally around 1,700 water main breaks in the area annually.