The fire that killed the four conscripts, aged 19 to 21, was ignited by Israeli shells fired in their support.
Israeli shell fired from a M109 howitzer," including one piece stamped "155mm.
All were killed when the Israeli shell struck the beach where they were having a picnic.
On April 18, several Israeli shells struck refugee compounds, killing 102 civilians sheltered there.
Qana has symbolic importance because Israeli shells killed many civilians there 10 years before in a similar incident.
Some Israeli shells hit the village during the fighting.
The synagogue was abandoned after Israeli shells hit the building, leaving rubble and debris strewn across the floor.
That stopped when Israeli shells hit an ambulance and then killed at least 75 refugees in a United Nations post.
An Islamic Jihad official said an Israeli shell fired in response killed one man and wounded others.
Last week the Israeli shells hit a school for the blind.
