Below are some photos showing the aftermath of the fire at Arlington's Great Meadows on the afternoon of April 17, 2009.  Click on the thumbnails for a larger view. 
Photos by John Bartenstein and David White of FoAGM.

Here are some more pictures from shortly after the fire by John Bartenstein: http://flickr.com/gp/jcblex/892735

And more pictures about a month later:  http://flickr.com/gp/jcblex/0Pjw12

Here's a link to some more after the fire pictures by Bill Sears: http://picasaweb.google.com/wlmsears/GreatMeadowsFireDamage42009?feat=directlink

Also more on the Lexington Minuteman website: http://www.wickedlocal.com/lexington/news/x297234870/Fire-officials-Lexington-may-never-know-what-ignited-the-Great-Meadows

Here's a report from the Lexington Fire Department:

We received the initial call just after 2:15 reporting a fire in the Meadows off of Brandon St at which time the wind was blowing wnw at approx 10 mph. (toward Golden Living Center). unfortunately this was on the opposite end of the fire, and provided no access.
 
Once arriving additional units were summoned and the wind direction changed, chasing the fire towards Circle Rd. Additional units were sent that direction.

By the end of the afternoon, we had 19 structural engines, 9 brush units and several additional resources for a total of 46 units responding.

There were two firefighter injuries.

Our estimates are a approximately 100 acres involved (estimates provided by MSP air wing) mostly wetlands, however the fire did damage at least three tree stands as well as some very minor damage to the boardwalk. The fire did impinge on several residential properties, coming as close as three feet to two homes and within 20 to 25 of several others.