The lead for this story included the who, the what and the when, but left out the how, why and where.
For the most part, this is a very general lead. The victims of the house explosion are not prominent figures, so they are not named. It also mentions the general timeframe, Saturday morning, but fails to specify the hour until later in the story. It also mentions that their house exploded, but it doesn't mention how it happened.
This is a very hard-news, straightforward lead. It presents the basic facts of the story, and then expands on the details as the story unfolds.
By using the word exploded in the lead, it catches the readers attention. Although they don't state the reason it exploded (because it is still under investigation), it's a strong enough word that it draws in the reader.
They also lead off with the who, because it was a woman and her three children that were injured, which also draws people in, because they tend to be more compassionate about women and children being injured in an explosion then men.