From the analysis of the @IDF operational systems, an enemy rocket barrage was carried out towards #Israel, which passed in the vicinity of the hospital, when it was hit.
According to intelligence information, from several sources we have, the Palestinian Islamic Jihad is responsible for the failed launch that hit the hospital. source
There is also some Al Jazeera footage that shows a rocket either failing or being intercepted, and then shortly afterwards a giant explosion on the ground below which is allegedly the Gaza hospital in question.
Assuming the AJ footage even shows the hospital area, known Hamas rockets don't have anywhere near the payload to do the kind of damage reportedly done to the hospital.
Edit: claimed video of the hospital strike. If true then for sure it's not an intercepted rocket of any kind.