Following catastrophic flooding in Ellicott City, MD, near Baltimore, July 30 (and the town is in a Piedmont canyon), there was a catastrophic apartment building explosion in Silver Spring MD August 11, 2016 at the Flower Branch Apartments.
There is no official cause, but reputable news stories indicate tenants had complained about the smell of gas (methyl mercaptan) some time before and that management had not addressed it adequately.
There are also reports of an ATF investigation.
Smaller apartment fires old older properties are quite common, and it's no secret that low and moderate income people (including many immigrants) live in housing that is somewhat unsafe and inadequately maintained. It is also true that tenant behavior can endanger others (link about renters insurance; blog posting about liability in another Maryland case).
WJLA today aired a story on home safety with gas lines, and suggested that homeowners turn off gas before they go out of town.
I’ve never heard this before. A reputable gas company plumber says that should not be done, and that appliances cannot be turned back on by the homeowner without plumbing help. Recently, I had a gas meter replaced outdoors by an upgrade, and the gas company did have to turn it off to install it, and retest the stove and furnace. However, homeowners should know where the gas shiutoff valve is. (It is considered good advice to turn off water before a home will be empty for more than a couple days.)
Many small businesses and rowhouses in Washington DC and other older cities have gas meters outside, where they are probably safer with respect to any leaks, but could present a target for vandalism.
Saturday night near the apartments, public access largely closed by police, but area of destruction visible from University Blvd at sight,
Access to Ellicott City from US-40 closed by police near Howard County government center.
Nearby Patapsco Valley State Park on US 40 open for visitors and hikers. Note the "Peaceful Pond" hike (like the 1981 movie "On Golden Pond"). This area is only about three miles from downtown Ellicott City but did not get nearly as much rain or flooding, for whatever reason.
The National Transportation Safety Board (as well as ATF) is looking into the possibility of issues with the Washington Gas infrastructure leading up to the meters for the building, rather than with the maintenance of the Flower Branch apts. or any possibility of deliberate acts. Gas pressure is "stepped down" at meters. Outdoor meters might not be as secure as indoor. Washington Gas says its own inspection has found no problems. The story by Dan Morse and Luz Lazo in the Washington Post Metro section today, Thursday. Recovery continues and much of the area is still off limits for the public,
Ellicott City will allow 4 days for residents to inspect the property, and then close much of Main Street for three weeks for major repairs (until at least Monday Sept. 12).
Update: Aug. 19
The official cause, according to NTSB and others, is a gas leak into an indoor meter room. Why wasn't this detected? Somebody was grossly negligent. The lawyers are going to get active on this.