BATTLE GROUND, Wash. -- A big brush fire near Interstate 5 in Southwest Washington forced crews to shut down lanes of the freeway Friday afternoon.

Officials said there an RV was also torched in the blaze. The fire started in the right southbound lane. Investigators think the RV had a mechanical problem that could have sparked the fire and said the driver did the right thing by pulling over.

The fire started near 319th near LaCenter. Lanes on I-5 were closed southbound for at least a two-hour delay.

Around 100 firefighters were called out to the 20-acre blaze, which they planned to monitor overnight for any hot spots.

Two homes had to be evacuated, but crews were able to save them and two other threatened buildings before letting the residents back in.