(CNN) -- An Israeli soldier was killed and four more injured by a mortar shell fired by their own forces on the Gaza border, a military spokesman said.
The incident took place Friday near the Israeli border town of Kissufim.
Military officials say a preliminary investigation shows it occurred after Israeli soldiers observed militants on the Gaza side of the border placing devices around the fence.
A firefight with the militants ensued, and the soldiers called in for mortar fire from another military location. One of the mortar shells hit the Israeli soldiers instead.
The incident is the latest in a spike of cross-border violence.
Gaza militants have increased attacks into Israel using crude rockets while the Israeli military is targeting militants more using airstrikes.
On Wednesday, two Palestinian men trying to cross the border fence from Gaza into Israel were killed by Israeli fire. On Thursday and Friday, Gaza saw consecutive Israeli air force strikes.
The Israeli military said that in the first week of the year, more than 10 rockets have been fired from Gaza into Israel's southern communities, and Israeli forces hit "several terror-related sites" in response to the missiles.