The Latest on the conflict in Syria, where a fragile cease-fire has begun but scattered violence and clashes continue (all times local):

12 p.m.

Members of the Islamic State group have stormed a northern border town that was captured months ago by Kurdish fighters, according to a Syrian rebel official.

Talal Sillo, a spokesman for the predominantly Kurdish Syria Democratic Forces, said Saturday that the IS fighters have attacked the town of Tal Abyad. The fighting began after midnight Friday and was still ongoing, Sillo said. Tal Abyad that has been held by Kurdish fighters since July.

The Britain-based Syrian Observatory for Human Rights also confirmed the fighting in Tal Abyad.

The Aamaq news agency, which is affiliated with the extremist group, reported that IS fighters launched a "surprise attack" on several areas in northern Raqqa province, where Tal Abyad is located. But the report did not provide further details.

Sillo told The Associated Press that SDF fighters "will finish the operation today."

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10 a.m.

Syria's state news agency says a car bomb has exploded on the edge of a government-held central town, killing two and wounding several others.

No one claimed responsibility for Saturday's blast on the eastern entrance of the town of Salamiyeh which came hours after a cease-fire brokered by Russia and the U.S. went into effect.

The Islamic State group has claimed responsibility for several bombings in Syria in recent weeks.

Opposition activists in different parts of Syria said the situation has been "cautiously calm" since the truce went into effect at midnight Friday.

The truce does not include either IS or al-Qaida's branch in Syria, known as the Nusra Front.

The Syrian government and 97 rebel and militant groups said they will abide by the cease-fire.