The Latest on Syria's conflict (all times local):

1:30 p.m.

Russian news reports say at least several private Russian military contractors have been killed by a U.S. strike in Syria.

Kremlin spokesman Dmitry Peskov refrained from comment, saying on Tuesday that the reports need to be verified.

Russian media said Russian private contractors were part of pro-government forces that advanced on oil fields in the eastern Deir el-Zour province and were targeted by the United States.

The U.S. military said last week it launched airstrikes on Syrian government-backed troops after as many as 500 attackers began what appeared to be a coordinated assault on Syrian opposition forces accompanied by U.S. advisers in the province of Deir el-Zour.

It said the strikes, which reportedly killed about 100 of the attackers, were in self-defense.

The Russian Defense Ministry said its troops weren't involved in the operation.

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1:25 p.m.

A monitoring group and a hospital manager say shells have landed near the only hospital in the northern Syrian enclave of Afrin, killing one person and wounding five.

Turkey is conducting a cross-border operation in the enclave to rout a U.S.-backed Syrian Kurdish militia that Ankara considers to be a "terrorist" group.

Jiwan Mohamed, the Afrin hospital manager, says the shell landed about 50 meters (yards) from the hospital on Tuesday, killing a taxi driver bringing in wounded.

It's the first shelling to hit the center of Afrin town since the offensive began on Jan.20.

Mohamed says the attack disrupted baby deliveries, cut electricity to one hospital section and sent panicked patients to the streets.

The Syrian Observatory for Human Rights says the shell landed near the hospital entrance.