U.S.-led coalition warplanes bombed Islamic State group positions overnight across four provinces in northern and eastern Syria, hitting a grain silo as well as the country's largest gas plant, activists said Monday, Associated Press reported.
Washington and its Arab allies opened their air assault against the extremist group last week, going after its military facilities, training camps, heavy weapons and oil installations. The campaign expands upon the airstrikes the United States has been conducting against the militants in Iraq since early August.
The Britain-based Syrian Observatory for Human Rights said coalition forces hit Islamic State group facilities overnight in Aleppo, Raqqa, Hassakeh and Deir el-Zour provinces. It said there were casualties, but that it did not have concrete figures.
Among the facilities hit was the entrance to Syria's largest gas plant, Conoco in Deir el-Zour province, and grain silo in the extremist-held town of Manbij in Aleppo province. It said the gas facility itself was not damaged.
Another activist group, the Aleppo Media Center, also reported the strike on the grain silo in Manbij, northeast of Aleppo city. It said the attack ignited a fire at the facility.
There was no immediate confirmation from the U.S. or its allies on the reported air raids.
More strikes Monday morning hit the town of Tel Abyad on the Syria-Turkey border, according to a resident on the Turkish side on the frontier.
Mehmet Ozer told The Associated Press by telephone that the raids hit an abandoned military base and an empty school, sending pillars of smoke and dust into the air. He said Islamic State fighters cleared out of the military about three or four months ago.
"They (the coalition) must not have fresh intelligence," Ozer said.
The Islamic State group has seized control of a huge chunk of Syria and neighboring Iraq, and has declared the establishment of a self-styled caliphate ruled by its strict interpretation of Shariah law there. Its brutal tactics, which include mass killings and beheadings, have helped galvanize the international community to go after the militants.
The U.S.-led campaign aims to roll back the extremists gains in Syria and Iraq, and ultimately to destroy the group.
The coalition includes Saudi Arabia, Bahrain, the United Arab Emirates, Qatar and Jordan. Several European countries also are contributing to U.S. efforts to strike the Islamic State group in Iraq, including France, the Netherlands, Denmark, Belgium and Britain.
The Observatory says at least 19 civilians have been killed so far in coalition airstrikes.
On Sunday, Human Rights Watch said that it had confirmed the deaths of at least seven civilians - two women and five children - from apparent U.S. missile strikes on Sept. 23 in the village of Kafr Derian in Idlib province. The New York-based group said two men were also killed in the strikes, but that they may have been militants.
It based its conclusions on conversations with three local residents.
"The United States and its allies in Syria should be taking all feasible precautions to avoid harming civilians," said Nadim Houry, deputy Middle East director at Human Rights Watch. "The U.S. government should investigate possible unlawful strikes that killed civilians, publicly report on them, and commit to appropriate redress measures in case of wrongdoing."