(UPDATE 4:35 p.m.):

Firefighters say the fire that engulfed a home on Fielding Street in Mount Vernon Thursday afternoon may have started outside.

"I don't want to speculate, but it was around the time school buses were dropping kids off and parents weren't around," said Andrew Duke, deputy chief, Fairfax County Fire and Rescue.

"A bystander on a cell phone called and said that a fire started outside the building and then spread to the inside," Duke told Patch.

Fire investigators are on the scene. The two adults and two children are being helped by the Red Cross to find shelter.

"That fire was huge," said neighbor Alan Smolins. "Luckily the siding of my house was not damaged."

Firefighters had the fire under control within about 4 to 5 minutes, firefighters said.

(UPDATE 4:20 p.m.):

Firefighters tell Patch that two adults and two children were displaced by the fire on Fielding Street. No one was injured, according to Andrew Duke, deputy chief, Fairfax County Fire and Rescue.

A vehicle was also burned during the fire.

The cause of the fire is to be determined and under investigation.

Firefighters responded to the fire at 3:13 p.m., after the call came in at 3:09 p.m. In all one rescue team, four fire engines and two fire trucks responded to the fire.

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A fire has engulfed a home Thursday afternoon in the 4100 block of Fielding Street in Mount Vernon.  Fairfax County Fire and Rescue firefighters were on the scene a little after 3 p.m.

Firefighters responded to a call at 3:09 that came in from a bystander, said a spokesman for Fairfax County Fire and Rescue.

No word yet on any injuries.

The home is located in neighborhood that is in a fairly heavily wooded area, with large trees. Mount Vernon Woods Park is down the street.

A number of county fire engines are currently at the scene. The power company was also on the scene due to live wires down on the front yard of the home.

Patch will update this story as we receive more information.