ANKARA, Turkey (AP) — Turkey's military says three soldiers were killed in northern Syria in an "accidental" airstrike by a Russian warplane.

The military says 11 other soldiers were wounded in the friendly fire incident on Thursday. The Turkish soldiers were inside a building that was hit by a Russian aircraft, according to a military statement.

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The statement said Russia expressed its sorrow and condolences for the incident while President Vladimir Putin called President Recep Tayyip Erdogan.

The incident comes after Turkey and Russia recently repaired ties that were strained by Turkey's downing of Russian jet near the border with Syria two years ago.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

A suspected rebel mortar attack struck a Syrian Red Crescent distribution center in the government-held city of Aleppo, killing a volunteer and two civilians who had come to seek assistance, the organization said Thursday.

According to the Syrian Arab Red Crescent and the Red Cross, the attack in the Hamadaniya neighborhood, which occurred on Wednesday, also wounded seven other volunteers.

The Britain-based Syrian Observatory for Human Rights confirmed the attack, saying that there were other mortar rounds that hit security checkpoints in the area on Wednesday. Syria's state news agency said mortar shells also hit other buildings in the neighborhood.

After years of heavy fighting, Syrian government forces drove the rebels out of eastern Aleppo in December, but the opposition still holds some areas on the city's outskirts. Fighting has continued around Aleppo and in other parts of Syria despite a Russia- and Turkey-sponsored cease-fire.

The cease-fire, in place since Dec. 30, has excluded areas where militant factions, the Islamic State group and Syria's al-Qaida affiliate, operate or hold ground. Syrian government troops and allied militias, as well Turkish troops, the U.S-led international coalition, and Russia have been going after IS in different parts of the country.

The push has lately focused on the IS-held town of al-Bab, northeast of Aleppo. Syrian government forces and their allies have been pushing from the south, aided by Russian airstrikes.

On Thursday, government troops seized a village south of al-Bab, bringing them less than 3 kilometers (1.5 miles) from the town, according to opposition monitors.

Meanwhile, Turkish troops, backing Syrian opposition fighters, have pushed their way from the western part of the town, entering the outskirts of al-Bab. The two advances have effectively encircled the militant group, which had set up strong fortifications around al-Bab, one if Islamic State group's last remaining strongholds in northern Syria.

Another fight against IS is raging in east and northeast Syria, where Kurdish troops, backed by the United States, are advancing against the IS in the militants' de facto capital of Raqqa. Meanwhile, government forces are battling an IS offensive in Deir al-Zour and another one in the central Homs province, around the ancient town of Palmyra.

Violence has also beset rebel- and opposition-held areas, including in Homs, where at least nine civilians were killed in suspected Russian or government airstrikes on Wednesday.