In response to Israel killing three Hamas terrorists recently, Hamas hit an Israeli school bus with a guided missile, critically wounding a 16-year-old boy and injuring the driver. Fortunately, all the other children had gotten off the bus just before the attack.
Hamas later tried to justify that violence by claiming that when it fired the missile, it did not realize its target was actually a school bus rather than a regular bus.
So apparently, the terrorist organization believes it is entirely permissible to launch missile attacks against a bus transporting civilians - so long as it's not a school bus. (Though in fact, Hamas has repeatedly targeted schoolchildren before.)
Some complain that Israeli counterattacks sometimes kill Palestinian civilians. But Israel attempts to avoid civilian casualties, while Hamas and other terrorist groups intentionally attack military and civilian targets alike.
That key difference should not be ignored.