DUBAI, United Arab Emirates - Iraqi authorities said Sunday that they have arrested 23 people linked to the Islamic State (ISIS) over plans to attack pilgrims during the Arbaeen of Imam Hussein in Karbala.

The suspects, including one woman, were detained in Baghdad, southern provinces, and the Middle Euphrates region, the Supreme Judicial Council said. The arrests were carried out by the Falcons Intelligence Cell under the supervision of the Karbala Investigative Court.

Officials said the group planned to plant roadside bombs along routes used by pilgrims, poison food served at rest stations, and set fire to service tents. One of the suspects accused of preparing the poison is a student in an anesthesiology department.

Every year, Iraq receives millions of Shiite pilgrims who flock to the city of Karbala to commemorate the 40th day after the anniversary of the killing of Imam Hussein in the seventh century. Many of the pilgrims travel from neighboring Iran, which has a majority Shiite population.

The Islamic State's ideology is particularly hostile to Shiite Muslims, whom they view as members of a deviant sect. In 2014, the group killed over 1,500 Shiite military cadets at Camp Spreicher in Tikrit in a sectarian atrocity that garnered widespread condemnation.

Iraqi Interior Minister Abdul Amir al-Shammari on Friday announced that more than three million foreign visitors have so far arrived in Iraq to participate in Arbaeen pilgrimage ceremonies.

Karbala Governor Nassif al-Khattabi, in a press conference, said that the network had foreign ties. “A cell affiliated with ISIS and linked to foreign entities, including Israeli intelligence, was arrested in Karbala for planning terrorist attacks targeting pilgrims during Arbaeen,” he said.

“Their goal was to plan terrorist acts, detonate explosive devices, and target security forces and service convoys. One of the operations took place inside a Husseiniyah on the Karbala-Najaf road.”

Investigators said ISIS recruited the cell through brainwashing, extremist propaganda, and linking them to clerics supportive of the group. Members were later forced to pledge allegiance to its leadership.

The Supreme Judicial Council urged families to watch for changes in their children’s behavior and report suspicious activity. It also advised organizers of service stations and husseiniyahs to keep unknown individuals away from food preparation areas and to tighten controls on supplies.