Of the 30 rockets, according to the Gaza NGO Safety Office, 11 of them either fell short in Gaza or exploded during the launch. That's a failure rate of nearly 37%.
We have seen in the past that several Gaza children have been killed by rockets meant to kill Israelis, including two or three children killed by Hamas rockets during Operation Pillar of Defense. Two children were killed by a single rocket during Hamas' Operation Oil Stain, a day before Israel launched Cast Lead. A two-year old girl was killed by a rocket explosion in Gaza in 2012.
In most of these cases, Hamas spokespeople, the media and many NGOs blame Israel. Because, to many, the truth isn't as important as anti-Israel propaganda.