Heavy shelling of so-called Islamic State positions has marked the start of a Turkish offensive to drive the militants away from the Syrian border.
Artillery and rocket launchers rained 224 rounds on the Jarablus area, the military said, as Turkish jets bombed their first targets in Syria this year.
Tanks could later be seen moving up to the border and opening fire.
Turkish special forces are already inside Syria as part of the operation to clear IS out of Jarablus.
If Jarablus falls, the jihadists will be pushed back from the Turkish border.
Turkey has also hit Syrian Kurdish forces in the region, determined not to let them fill the vacuum if IS leaves, the BBC's Mark Lowen reports from Gaziantep, near the Syrian border.
The concern in Ankara is that the Kurds could create an autonomous area close to the border which might foster Kurdish separatism within Turkey itself, our correspondent says.