I find it hard to believe that Hamas would fire rockets it knows to be inaccurate on Jerusalem. Put aside the city's many mosques and Muslim shrines; Jerusalem and its environs are also home to hundreds of thousands of Palestinians.
On the other hand, Hamas has never been overly concerned with creating Palestinian casualties. Victims of collateral damage are often re-cast as martyrs to the cause. What is the cause, by the way? I'm not sure at this moment. Hamas seems to be inviting its own destruction at this moment -- especially if these reports of attacks on Jerusalem are true.