Several people — including a number of children — also drowned over the weekend as they attempted to flee the besieged city by crossing the Euphrates River.
Tens of thousands of displaced residents have returned to the Anbar provincial capital in the past two months, mostly from camps east of the city where they took refuge prior to the army's advance late last year.
Eight senior figures from the Islamic State were reportedly killed during a meeting in western Iraq, but Abu Bakr al-Baghdadi did not appear to be among them.
The UN issued a statement about the alleged incident on the same day a watchdog group reported that as many as 1,247 civilians have been killed by airstrikes in Iraq and Syria.
The militants decisively captured the capital of Iraq’s largest province on Sunday despite a spate of US airstrikes intended to keep the city from falling.
Officials in Anbar Province expect that IS fighters will overrun the portion of Ramadi under government control if the US-led coalition does not provide adequate air support.
The strikes move American military operations closer to the Syrian border.