Five people were wounded Sunday when a mortar shell crashed into a house in Turkey, kilometers from a fierce battle between Kurdish fighters and Islamic State militants in neighboring Syria.
Witnesses said the injuries were not life-threatening. The origin of the shell was unclear.
The fighting near the Syrian border town of Kobani, also known as Ayn al-Arab, is entering a third week. Turkey has deployed its military to the frontier, but has not yet intervened.
Turkish lawmakers voted last week to allow troops to engage in Syria and Iraq, where the Islamic State group is leading an offensive to gain ground.
The U.S. military said Sunday that it destroyed IS tanks and firing positions in two Syrian cities (Al Mayadin and Raqqa) during the latest round of air strikes aimed at supporting Kurdish fighters and so-called moderate Syrian rebels who are countering the Islamic State offensive.
None of the most recent strikes were near Kobani, where a Kurdish defense chief told VOA last week that fighters felt abandoned by the U.S.-led coalition.
U.S. aircraft also bombed IS targets in Iraq near Fallujah, Hit and Sinjar on Sunday, hitting mortar teams and vehicles.
In another development, U.S. Vice President Joe Biden has apologized to Turkish President Recep Tayyip Erdogan for comments suggesting Turkey had allowed Islamist fighters to pass through its border into Syria and helped arm militant groups.
A White House statement says Biden called Erdogan Saturday and "apologized for any implication that Turkey...had intentionally supplied or facilitated the growth" of Islamic State militants "or other violent extremists in Syria."
While answering questions Thursday after a speech, Biden said the Turkish president admitted to him that Ankara "had let too many people through." On Saturday, Erdogan reacted angrily, saying he had never made such a comment.
Some information for this report was provided by AP, AFP and Reuters.