Editor's note: Read a version of this story in Arabic.
(CNN) -- Four young men were burned to death in Hama province Wednesday when regime forces set fire to a house, an opposition group said. They are among dozens killed Wednesday in the bloody conflict, now a year and a half old. The group, the Local Coordination Committees of Syria, said the number of documented deaths exceeds 26,000 since March 2011.
U.N. official: Situation for children is 'dire'
Leila Zerrougui, the U.N. envoy for Children and Armed Conflict, cast an extremely pessimistic view of life in Syria for children.
"My staff and other United Nations colleagues have documented government attacks on schools, children denied access to hospitals, girls and boys suffering and dying in bombardments of their neighborhoods, and also being subject to torture, including sexual violence, sometimes for weeks," she told the Security Council in prepared remarks.
Zerrougui callled the situation in Syria 'dire' and said she had asked the government to call on the Syrian military to evacuate schools as a top priority. She also said non-state groups have committed violations and one, the Free Syrian Army, "may have children associated with their forces."
Opposition: Capital, suburbs engulfed in fighting
At least 150 people were killed in fresh violence Wednesday, including 72 in Damascus and its suburbs, opposition activists said.
Twenty people were executed in the capital's Jobar neighborhood, the LCC said.
Warplanes shelled civilians gathered at a bakery in Deir Ezzor province, the LCC said, killing three people and wounding more than 15.
Regime reports strides in Aleppo, other cities
Government forces inflicted "heavy losses" against "terrorists" in Aleppo, the nation's most populous city, and its countryside, the state-run Syrian Arab News Agency said Wednesday.
They destroyed an ammunition warehouse and seized weaponry in the Aleppo operations, the agency said.
Soldiers also said they cleared a Damascus countryside neighborhood of militants, destroyed an ammunition warehouse in Homs and seized a truck in Hama loaded with weapons and ammunition.
Rebels celebrate taking Turkish border crossing post
Syrian rebels seized a crossing at the Turkish border Wednesday, tearing down the Syrian flag and ripping posters of President Bashar al-Assad, Turkish media reported.
Rebels fired into the air in celebration after taking control of a customs building at the Tal Abyad border gate, the Anadolu Agency reported. "Their kinsmen in Turkey joined them in their celebration from across the Turkish side of the border," Anadolu said.
Fighters have been trying to take control of border crossings to secure a haven near Turkey, a country sympathetic to the Syrian opposition movement.
Iranian foreign minister visits
Al-Assad met with Iranian Foreign Minister Ali Akbar Salehi on Wednesday, the latest meeting with a country that has defended the Syrian regime.
Salehi "stressed the need to hold talks between Syrian government and opposition groups to settle the dispute," Iranian media said. The country "is ready to broaden cooperation with Syrian government to help reduce shortcomings in Syrian public life and improve life standard of Syrian people," he said.
Before the meeting, Salehi met with Syrian Foreign Minister Walid Moallem. Salehi also met in Cairo, Egypt, this week with his Turkish and Egyptian counterparts on Syria.
The U.S. Department of the Treasury has placed sanctions against entities that support the regime's efforts to get arms and communications equipment.
Syria's Army Supply Bureau and Belarus-based Belvneshpromservice were designated under an order targeting the assets of proliferators of weapons of mass destruction and their supporters.
"Today's actions seek to disrupt the flow of weapons and communications equipment to the Syrian regime and help prevent their use against the Syrian people," said David S. Cohen, under secretary for terrorism and financial intelligence.
CNN's Saad Abedine, Yesim Comert, Joe Sterling and Holly Yan contributed to this report.