A Somali man detonated an explosives-rigged armored vehicle inside the base, while a Tajik and a Syrian blew up a Humvee and a truck in the area, ISIS said in an online statement.

A military intelligence officer said the Monday attack against a federal police base located between Samarra and Tharthar killed 47 -- 40 police and seven pro-government paramilitaries.

Haider al-Ramahi, an official from a Shiite political party that had earlier helped some of those killed join the police, put the toll at 48 dead.

The police killed were buried Tuesday in the Shiite holy city of Najaf, south of Baghdad.

Mohammed al-Bayati, a relative of one of the dead, said that “the martyrs are from Turkmen families displaced to Najaf after the fall of their town” to ISIS.

“They joined the... police to take part in liberating their areas and Iraq in general from (ISIS) control,” he said.

The area where the attack took place is being used in a military operation aimed at cutting off ISIS’ supply lines in Anbar, a province west of Baghdad where the militants overran the city of Ramadi last month.

Over the past year, ISIS has seized a formidable arsenal of military vehicles, weapons and ammunition from retreating Iraqi forces as its fighters swept through much of the country’s Sunni Arab heartland.

In recent days, security forces have successfully repelled several suicide attacks involving vehicles thanks to anti-tank systems, but not all forces have access to those weapons.

On Tuesday, members of the U.S.-led coalition carrying out air raids against ISIS and providing training and weapons to Iraqi forces held talks in Paris on a string of major battlefield gains by the militants in Iraq and Syria.