I see 3 possibilities:
-natural gas
-gasoline
-thermobaric warhead


If you look through Google's images of natural gas explosions, you'll see houses with one wall blown off. Natural gas does not usually detonate (i.e. the ignition spreads at subsonic speed) so even if an entire house is filled with natural gas, it's only the one room where it initially catches on fire that will experience high enough pressure to blast the walls into the street. After that wall is out of the way, a jet of flaming gas spews out the opening, like what happens when you throw a plastic lighter into a bonfire. It seems very unlikely that a natural gas explosion could level 2 houses, rip off half of 2 more, and kick in people's front doors from a block away. Not impossible, but unlikely.

Gasoline vapor is more likely to detonate (especially with the additives used during winter in the US gas supply such as butane), but if gasoline was used then we'll hear about it soon enough. Insurance companies will be looking for it.

Hellfire missiles can be fitted with thermobaric warheads, and those could have leveled 3 houses without leaving a crater. The homeowner's boyfriend is a known con-man, someone it would be easy to turn into scapegoat. He was also at a casino at the time, which means he was probably tagged by cameras & facial recognition software which could confirm he was away from the house at the time - convenient if you want to frame him for arson and insurance fraud (if you need a place to dump a couple of misfired missiles, aim for this guy's empty house and you'll have the perfect cover story).