BAGHDAD — Iraqi investigators were probing a mass grave on Tuesday discovered by troops advancing on the Islamic State-held city of Mosul, where soldiers have captured a sliver of land but later halted their advance.

It appeared to be the latest of several mass graves found in territory retaken from IS, which massacred hundreds of people as it swept across northern and central Iraq in 2014 and is believed to have waged a brutal crackdown since the start of the Mosul offensive.

Associated Press footage from the site shows bones and decomposed bodies among scraps of clothing and plastic bags dug out of the ground by a bulldozer after Iraqi troops noticed the strong smell while advancing into the town of Hamam al-Alil on Monday.

“Investigators flew in this morning and are on their way to the grave to conduct examinations and determine the cause of death,” said Haider Majeed, a Cabinet official in charge of mass grave investigations.

The first officials at the site said the grave, behind an earthen embankment near an agricultural college, likely holds about 100 bodies, many of them decapitated. The town lies some 30 kilometers (19 miles) from Mosul.

It was unclear who the victims were, but a soldier at the site pulled a child’s stuffed animal from the scraps of clothing and rotting flesh, swarming with flies.