Turkey's state-run agency says a salvo of rockets has struck southern Turkey, wounding four people.

The Anadolu Agency said three rockets struck the Turkish town of Kilis early Thursday.

The rockets were fired from Islamic State group-controlled territory in Syria, according to the private Dogan News agency.

It said one policeman was among the wounded and broadcast images of damaged buildings and vehicles.

Such incidents have become a regular occurrence in the border town, which is home to a significant Syrian refugee population.

Turkish President Recep Tayyip Erdogan warned IS on Wednesday that no attack on Turkey would go unanswered.

Cross-border fire has left 20 people dead and dozens of others wounded this year.

The Turkish military typically fires back in line with its rules of engagement.