Israel, the U.S. government and independent security experts said Wednesday the preliminary evidence for a deadly explosion at a Gaza hospital compound pointed to a local militant group, casting doubt on Palestinian claims that an Israeli airstrike was responsible.

Independent analysts poring over publicly available images of Tuesday’s explosion at Al-Ahli Arab Hospital in Gaza and its aftermath say the blast site doesn’t bear the hallmarks of a strike with a bomb or missile of the types usually used by Israel.