BEIRUT (AP) — The Latest on the conflict in Syria (all times local):
The United States says the truce in the Syrian city of Aleppo could expire in a couple of hours.
State Department spokesman Mark Toner says the U.S. understanding of the temporary truce is that it began Wednesday at 12:01 a.m., Damascus time. He says the period of calm was agreed on for 48 hours.
That would mean it expires at 12:01 a.m. Friday.
Toner says the U.S. is trying to secure a longer-term extension of the cessation of hostilities.
Syrian and Russian officials have said the truce began Thursday, meaning it would expire Saturday.
The White House says an airstrike that killed at least 28 people in northwestern Syria is "indefensible."
White House spokesman Josh Earnest says there's "no justifiable excuse" for an airstrike targeting innocent civilians who have already left their homes to flee violence. He says the situation is heartbreaking.
Earnest says it's too early to say whether Syrian President Bashar Assad's forces conducted Thursday's attack. But he says he believes no U.S. or coalition aircraft were operating in the area.
Earnest says if it turns out Assad's government was responsible for using force against civilians, "it would not at all be the first time."
An activist monitoring group says at least 28 people have been killed in an airstrike on a refugee camp in northwestern Syria, near the Turkish border.
The Britain-based Syrian Observatory for Human Rights says there are women and children among the casualties from the strike that hit the camp for the internally displaced in rebel-held territory near Sarmada, in Syria's northwestern Idlib province.
The Local Coordination Committees, another activist group, says more than 30 are dead. The camp is home to hundreds of people who have fled from the surrounding Aleppo and Hama provinces.
Videos circulating on social media said to be from the camp show at least a dozen tents burned to the ground, charred bodies and bloodied women and children being loaded onto a pickup truck.
Syrian pro-opposition activists say an airstrike has hit a refugee camp in northern Syria, near the border with Turkey, killing and wounding dozens of people displaced from the country's devastating civil war.
The Britain-based Syrian Observatory for Human Rights says a camp in near Sarmada, in the northwestern Idlib province near the Turkish border, was struck on Thursday afternoon.
It was not clear who carried out the airstrike and the Observatory did not immediately have a breakdown of the casualties.
The Local Coordination Committees network says first responders are at the site, extinguishing fires that have erupted in the impacted zone. A photo that was posted on the LCC's Facebook page shows at least a dozen tents burned to the ground.
A Lebanese TV station embedded with the Syrian army says Syrian rebels are waging an offensive on a government-held village south of the city of Aleppo.
Al Mayadeen TV, broadcasting live from near the fighting, says armed groups launched their assault for Khan Touman earlier in the afternoon on Thursday.
The TV says government jets are bombing rebel positions outside the village. Bomb blasts are seen in the station's feed from the hilly countryside.
The Britain-based Syrian Observatory for Human Rights, which monitors the conflict, says the clashes are fierce.
Khan Touman is located 4 miles (6 kilometers) from the outskirts of Aleppo, Syria's largest city and key recent battleground in the running conflict.
A 48-hour cease-fire covering the city is set to expire Friday night.
Renowned Russian conductor Valery Gergiev has led the Mariinsky orchestra from St. Petersburg in a concert at the ancient Syrian city of Palmyra.
The concert, dubbed "With a Prayer for Palmyra," was held in the amphitheatre in Palmyra on Thursday afternoon and the program included Bach's Chaconne for Solo Violin, a cello piece by Rodion Shchedrin and Sergei Prokofiev's First Symphony.
The audience included Russian servicemen, including those who have been doing demining in Palmyra after Islamic State militants were routed from the city and it was retaken by Syrian government troops with the help of Russian airstrikes.
The IS militants badly damaged the world famous archaeological site of Palmyra. In opening remarks, Gergiev said that with the concert, "we protest against the barbarians who destroyed monuments of world culture."
There was also a video linkup in which Russian President Vladimir Putin addressed the audience.
Putin said he regards the concert "as a sign of gratitude, remembrance and hope - of gratitude to all those who fight terrorism without sparing one's own life; of remembrance for all victims of terror, regardless of the place and time of crimes against humanity; and of course hope not just for the revival of Palmyra as a cultural asset of all humanity but for the deliverance of modern civilization from this terrible ill, from international terrorism."
Syrian state TV is reporting that two explosions in a village in the central province of Homs have killed and wounded several people.
The channel says the first blast in the village of Mukharam al-Fawkani was a car bomb and the second was a suicide attacker wearing an explosive belt. The report gave no breakdown of the casualties from the blasts.
The Islamic State group had claimed responsibility for similar attacks in Homs province in recent months that killed scores of people.
The violence came as the northern city of Aleppo witnessed relative calm as U.S. officials announced an agreement had been reached with Russia to extend Syria's latest fragile cease-fire to the deeply contested northern city.
The Syrian military said the truce, which began at 12:01 a.m. Thursday (5 p.m. Wednesday EDT) would last only 48 hours.
Turkey's state-run news agency says a salvo of rockets has struck southern Turkey, wounding four people.
The Anadolu Agency said three rockets struck the Turkish town of Kilis early Thursday.
The rockets were fired from Islamic State group-controlled territory in Syria, according to the private Dogan News agency.
It said one policeman was among the wounded and broadcast images of damaged buildings and vehicles.
Such incidents have become a regular occurrence in the border town, which is home to a significant Syrian refugee population.
Turkish President Recep Tayyip Erdogan warned IS on Wednesday that no attack on Turkey would go unanswered.
Cross-border fire has left 20 people dead and dozens of others wounded this year.
The Turkish military typically fires back in line with its rules of engagement.