Earlier Turkish troops fired at the field base of USA special forces in Syria.
One Army officer who has deployed to northeastern Syria and has knowledge of the situation said that multiple rounds of 155mm fire were launched from Turkey's side of the border and that they had a "bracketing effect" in which shells landed on both sides of the United States outpost.
The US official said Friday's artillery strikes near US troops around Kobani are evidence Turkey is operating beyond the areas it had indicated to the US.
The assault has raised worldwide alarm over its mass displacement of civilians and the risk it could trigger a revival of an Islamic State insurgency in Syria, with a heightened possibility of IS militants escaping Kurdish prisons.
Erdogan has threatened to send them to Europe if the European Union does not back his assault.
An AFP correspondent in the area said Turkish troops and allied Syrian rebels had entered the town but had yet to capture it.
Germany has halted arms exports to Turkey, a North Atlantic Treaty Organisation ally, and France said sanctions against Turkey would be discussed at next week's European Union summit. "Mine and booby trap searches are being carried out".
The Kurdish-led Syrian Democratic Forces (SDF), in which the YPG comprises the main fighting element, denied losing the centre of Ras al Ain.
"Now the SDF's attack has started and there are very fierce clashes", Qamishlo told Reuters. Intense gunfire also resounded within Ras al Ain in the early hours, while warplanes could be heard flying overhead.
The statement didn't say whether Macron urged US forces to intervene.
In making the mediation offer, Iranian Foreign Minister Mohammad Javad Zarif referred to a 21-year-old security accord that required Syria to stop harbouring Kurdistan Workers' Party (PKK) militants waging an insurgency against the Turkish state.
Heiko Maas said: "Against the backdrop of the Turkish military offensive, the Federal Government will not issue any new permits for all military equipment that could be used by Turkey in Syria".
Egypt called the emergency meeting to discuss what it called Turkey's "blatant aggression" against Syria's sovereignty.
McClure said this is not an isolated incident and similar things are happening in other prisons holding ISIS suspects.
Ankara says its forces' mission is to establish a safe zone run by its mainly Arab Syrian allies in which some of the 3.6 million mostly Arab refugees from Syria can be rehoused.
Stoltenberg spoke at a news conference in Istanbul with Turkish Foreign Minister Mevlut Cavusoglu.
"We don't. negotiate with terrorists". "The only thing to be done is for these terrorists to lay down arms".
"They know exactly where US forces are", Milley said at a joint Pentagon news conference with Defense Secretary Mark Esper.
Erdogan said on October 11 that Turkey won't stop until the YPG withdraw below a 32 kilometer deep line.
The towns of Ras Al Ain and Tal Abyad further west have been primary goals of the Turkish offensive and have both come under heavy bombardment.
"Most of the Syrian National Army fighters, the friendly indigenous components of the operation, are local Arabs and Turkmens from the region", he said.
As part of the operation, PKK/PYD-YPG terrorist targets were effectively hit by land and air, it said. It did not say if any Islamic State prisoners had escaped.
French President Emmanuel Marcron said the action could lead to a resurgence of Islamic State activity.
The official said Kurdish fighters had temporarily pulled back from the town before launching a counter-offensive against Ankara's forces.
France has suffered multiple deadly attacks by IS-linked radicals.