Updated

Israel's chief military spokesman says if violence drags on along the Gaza border, Israel will expand its reaction to strike the militants behind it.

Brig. Gen. Ronen Manelis says Saturday the military has thus far restricted its response to those trying to breech its border but it attacks continue it will go after militants "in other places too."

Thousands of Palestinians marched to Gaza's border with Israel on Friday in the largest such demonstration in recent memory. Fifteen Palestinians were killed by Israeli fire on the first day of what Hamas organizers said will be six weeks of daily protests against a border blockade. It was the bloodiest day in Gaza since the 2014 cross-border war between Israel and Hamas.

Manelis says all those killed were engaged in violence.