Three bombers mingled with refugees that had fled jihadi strongholds in Iraq.
The group is about to lose Mosul, most of Raqqa, and has already lost most of its funding.
The group destroyed the mosque earlier this month amidst its final stand for the city.
The sniper stopped an ISIS ambush on Iraqi security forces with a shot from over two miles.
The Syrian Observatory for Human Rights says the strike in Mayadin, eastern Syria, killed 44.
The group has lost a quarter of the eastern Syrian city within weeks.
Children gathered in squares to celebrate the holiday with ISIS ousted from much of their former Iraqi capital.
The mosque was used by the group's leader Abu Bakr al-Baghdadi to declare a caliphate in 2014.
Human Rights Watch have condemned the "horrific, long-lasting harm" that the weapon could inflict upon civilians in ISIS territory.
There has only been one reported instance of a chemical weapons attack this year, new analysis shows.
Former Iraqi envoy to the U.S. asks: Do Iraqis want a united or divided country?
The civilians were escaping the city using a dinghy to cross the Euphrates.
Iraqi paramilitaries announce the liberation of a key ISIS stronghold.
Murad has joined forces with human rights lawyer Amal Clooney to fight for an investigation into ISIS's crimes against humanity.
Rayan Meshaal was apparently killed in the city of al-Mayadin.
U.S. Army Major General Joseph Martin, head of ground forces for the U.S.-led coalition fighting ISIS, tells Newsweek of the complex offensive that Iraqi forces are facing.
The militant group is reportedly gathering its top chemical weapons experts in the Euphrates River Valley.