As the Iraqi government moved to strengthen its defenses Sunday, the Islamic militant group that captured two major cities last week posted graphic photos that appeared to show its fighters executing dozens of Iraqi soldiers.

The Associated Press reports:

The pictures on a militant website appear to show masked fighters of the Islamic State of Iraq and the Levant, or ISIL, loading the captives onto flatbed trucks before forcing them to lie face-down in a shallow ditch with their arms tied behind their backs. The final images show the bodies of the captives soaked in blood after being shot.

The grisly images could further sharpen sectarian tensions as hundreds of Shiites heed a call from their most revered spiritual leader to take up arms against the Sunni militants who have swept across the north. ISIL has vowed to take the battle to Baghdad and cities further south housing revered Shiite shrines.

A car bomb meanwhile exploded in central Baghdad, killing 10 and wounding 21, according to police and hospital officials. Baghdad has seen an escalation in suicide and car bombings in recent months, mostly targeting Shiite neighborhoods or security forces.

While the city of seven million is not in any immediate danger of falling into the hands of the militants, Sunday’s bombing could raise tensions. Food prices in the city have risen, twofold in some cases, because of disruption to transport on the main road heading north from the capital.