Absolutely. The history of Islam has been almost as filled with intramural wars as the history of Christendom. It's just that they seldom speak against or fight each other for being too hard on unbelievers.
Muslims will not condemn other Muslims, even when they commit the most heinous crimes. Anyone who isn't a Muslim has no standing in the eyes of the Muslims. And, anything that a Muslim does to a Christian or other non-muslim is just fine in the eyes of all Muslims.