"There has been no response from the Turkish side, so far," our correspondent said. The military said earlier it had fired back on Sunday after two mortar bombs crossed the border.
Adding that shells hit at least three homes and a school in Ain al-Arab, a largely-Kurdish town known to its residents as Kobane. "There were no reports of injuries, as the targets were vacant," she said.
More than 150,000 Syrian Kurds have streamed into Turkey since last week, as IS fighters pressed towards Ain al-Arab.
"Things are intensifying. This doesn't mean ISIL are advancing, because they have long-ranging artillery, but it shows that the fighting is ongoing," Dekker said.
Meanwhile, US-led coalition air raids targeted towns and villages in northern and eastern Syria controlled by IS. The Syrian Observatory for Human Rights, a UK-based group that monitors the violence in Syria, said the coalition targeted grain storage areas in the IS stronghold of Manbij, east of Aleppo, killing workers and not fighters.
The observatory reported that 10 air raids targeted various parts of the province of Idlib, killing at least one child and six others, including five members of the same family. The purported civilian casualties would add to the 19 civilians that the Observatory says have already been killed in raids against the group. Anti-West sentiments are increasing as more civilians are killed.
An activist in an IS-held town said: "These air strikes are causing an economic crisis. Winter is around the corner and people need heating oil. Most of the oil facilities are not operational - even those which haven't been hit because people are scared."
On Sunday, Human Rights Watch said that it had confirmed the deaths of at least seven civilians - two women and five children - from apparent US missile strikes on September 23 in the village of Kafr Derian in Idlib province. It based its conclusions on conversations with three local residents.