Raqqa, the former capital of the so-called ISIS Caliphate, has been placed on lockdown by the U.S.-backed Syria Democratic Forces (SDF) after reports that ISIS terrorists have infiltrated the city and are planning to carry out several bombings, according to a report from Reuters.

Late Saturday night, the SDF commanders in Raqqa “declared a state of emergency,” implemented a three-day mandatory curfew, and erected several manned checkpoints on the city’s roads. Currently, SDF forces along with Raqqa’s internal security personnel are conducting sweeps and raids to root out the ISIS sleeper cells.

The city, which was liberated by the SDF in October of last year after an intense and prolonged battle, will remain on lockdown until Tuesday. During the curfew, none of the 100,000 or so residents will be permitted to enter or leave the city.

While ISIS may have sleeper agents inside Raqqa, they are still without a permanent base of operations. The SDF along with the U.S. and coalition partners began a new offense in May of this year, which has kept the remnants of the Islamic State on the run. Dubbed Operation Roundup, the focus of the mission is to find and destroy the remaining ISIS fighters in the Middle Euphrates River Valley.

Meanwhile, Syrian President Bashar al-Assad’s forces are engaged in fighting in Southwestern Syria near the Jordanian border and the Golan Heights. Despite the heavy damage done to Syrian cities since the civil war began, Assad stated earlier that he would not accept aid money from Western countries, according to a report from Reuters.