It said all the Palestinians were members of the Hamas "rocket" division.
Israelis also attacked another vehicle being used to evacuate those wounded in the first attack.
In the small hours of Wednesday, Israeli troops killed two residents of Gaza, one of them a member of the radical group Islamic Jihad. The other, a local farmer, was shot dead near the border with Israel.
Israel says missile strikes and raids against militants in Gaza are being carried out in an effort to halt Palestinian rocket attacks on Israel's southern cities and towns.
More than 230,000 Israelis live within range of Palestinian rocket fire. More than 4,200 rockets and mortar rounds have been fired at southern Israel since the radical Islamic group Hamas seized power of the Gaza Strip in June last year,
