By Daren Butler and Suleiman Al-Khalidi
ISTANBUL/AMMAN (Reuters) - Turkey said a Kurdish militia killed two people in mortar attacks from northern Syria on Monday, in an escalation of cross-border retaliation following Turkish air operations at the weekend and a deadly bomb attack in Istanbul a week ago.
Turkey's armed forces said it was responding, and a senior security official told Reuters that Turkish jets had again started hitting targets in northern Syria.
In the latest in a series of tit-for-tat attacks, several mortar shells hit a border district in Turkey's Gaziantep province, leaving a child and a teacher among the dead and at least six wounded, said Interior Minister Suleyman Soylu said.
A pregnant woman initially reported as killed was badly wounded and is under treatment in hospital, Soylu said later.
Local governor Davut Gul said five rockets had hit a school, two houses and a truck near the Karkamis border area. Broadcaster CNN Turk said the attack was launched from Syria's Kobani area, controlled by the Syrian Kurdish YPG militia.
Turkish warplanes had carried out strikes in Syria and Iraq on Sunday, destroying 89 targets linked to the outlawed Kurdistan Workers Party (PKK) and the YPG, which Ankara says is a wing of the PKK.
In a statement, the Turkish defence ministry said 184 militants were killed in operations on Sunday and Monday. It said the operations had included air strikes and land-fired weapons.
Turkey said its weekend operation was in retaliation for the bomb attack in Istanbul last week that killed six people, and which authorities blamed on Kurdish militants. The PKK and YPG-led Syrian Democratic Forces (SDF) have denied involvement in the Nov. 13 bombing on a busy pedestrian avenue.
Washington has allied with the SDF in the fight against Islamic State in Syria, causing a deep and lasting rift with NATO ally Turkey.
The United States urged de-escalation in Syria and said it opposed "any uncoordinated military action in Iraq that violates Iraq's sovereignty," U.S. State Department spokesperson Ned Price said in a statement.
An SDF spokesman had said the weekend Turkish strikes destroyed grain silos, a power station and a hospital, killing 11 civilians, an SDF fighter and two guards. It also said it would retaliate.
During the weekend violence, eight Turkish security personnel were wounded in YPG rocket attacks from Syria's Tal Rifat on a police post near a border gate in Kilis province, Ankara said.
On Monday, Turkey struck a Syrian army outpost west of Kobani where a YPG army barrack is located, an SDF source said. The outpost is one of several where the Syrian army was brought in to prevent the Turks from attacking the SDF.
Turkey has backed rebels fighting to topple Syria's President Bashar al-Assad, and cut diplomatic relations with Damascus early in the 11-year conflict.
Turkey's armed forces have conducted several large-scale military operations in recent years in northern Iraq and northern Syria against the YPG, PKK and Islamic State.
President Tayyip Erdogan said Turkey's operations would not be limited to an air campaign and could involve ground forces.
"Our defence ministry and our general staff decide together how much of the land forces should take part. We make our consultations, and then we take our steps accordingly," he was quoted by Turkish media as saying on a flight from Qatar.
The PKK launched an insurgency against the Turkish state in 1984 and more than 40,000 people have been killed in the conflict. It is considered a terrorist organisation by Turkey, the United States and the European Union.
(Additional reporting by Ece Toksabay and Orhan Coskun in Ankara; Editing by Jonathan Spicer, Toby Chopra, Gareth Jones and William Maclean)