DAMASCUS, May 13 (Xinhua) -- An explosion rocked Syria's northern province of Raqqa on Monday morning, targeting a member of the Kurdish-led Syrian Democratic Forces (SDF), a war monitor reported.

The explosion was caused by an explosive device placed under a car that belongs to a member of the SDF, said the Syrian Observatory for Human Rights.

The Britain-based watchdog group said the explosion rocked near the White Garden in Raqqa, which also caused damage in the area.

The explosion comes hours after another explosive device went off in Raqqa overnight, causing damage.

It is not yet clear who is behind the explosions in Raqqa, but such acts are usually carried out by sleeper cells with the Islamic State (IS) group.

It is also worth noting that Raqqa was the de facto capital of IS, and the SDF, with the help of the U.S.-led coalition, captured it in 2017.

Meanwhile, the observatory said that sleeper cells of IS carried out shootings in the eastern Euphrates River region in eastern Syria, which is also controlled by the SDF.

It said the IS militants continue their activities in areas controlled by the SDF in the eastern Euphrates region in the eastern countryside of Deir al-Zour.

The SDF has recently stripped IS of areas it controlled in the eastern Euphrates.