Israeli aircraft fired missiles at a group of Palestinian gunmen early Saturday, killing four and wounding 15, Palestinian security officials said.
Two of the dead were identified as members of the Islamic militant Hamas group, security officials said. Two of the wounded were in serious condition. A woman was also among those hurt.
Witnesses said ambulances driving to the scene came under fire.
The gunmen were targeted east of Gaza City, near the Gaza-Israel border.
More than a dozen Israeli tanks also moved in the area, and security officials reported exchanges of fire between the Israeli forces and Palestinian gunmen.
The Israeli military said the incident began when an anti-tank missile was fired at an Israeli bulldozer. Troops responded with fire from the air and the ground. The army said it knew of at least one dead and several wounded gunmen.