RABAT, Morocco (AP) — Moroccan authorities say police arrested five people suspected of plotting suicide bombings and being part of an extremist network linked to the Islamic State group.

One suspect set off an explosive as police moved in during coordinated raids in four cities, and one officer was injured when another suspect attacked him, according to a statement Thursday from the Central Bureau of Judicial Investigations cited by the state news agency MAP.

Authorities seized explosive belts, detonators, pressure-cookers loaded with nails, ammonium nitrate and other chemicals suspected of being used for explosives, and IS paraphernalia, the statement said. The police operations were carried out in Tangiers, Tiflet, Temara and Skhirat.

The statement said the suspects were in the “advanced stages” of plotting suicide bombings against unidentified sensitive targets.

More than 1,000 Moroccans are believed to have joined IS between 2013 and 2017 as it seized territory across Syria and Iraq. Moroccan authorities carry out periodic sweeps of terrorism suspects.