Two boys aged 12 and 14 were among seven Palestinians shot and killed by Israeli soldiers on Friday.
The victims had gathered at the border of the Gaza Strip with thousands of others for weekly protests that have been going on for the last six months.
Israel's military said troops resorted to live fire and an air strike after demonstrators threw explosive devices and rocks. The soldiers also wanted to prevent breaches of the border fence from the Islamist Hamas-controlled enclave.
Health officials in Gaza said more than 500 people were wounded - 89 of them by gunshots.
At least 191 Palestinians have been killed since the Gaza demonstrations began on March 30. Protesters are demanding the right of return for Palestinians driven out on Israel's founding in 1948, and the easing of an economic blockade.
A sniper in the Islamist Hamas-controlled enclave has killed one Israeli soldier and incendiary devices flown over the border by Palestinians using kites and balloons have set off fires that destroyed forest and farmland in Israel.