“Time and again, over the years, UNRWA is being abused by gunmen from different terrorist factions who are using UN facilities to stockpile weapons, to fire rockets from, to steal UNRWA humanitarian equipment and to cause damage and fire in UNRWA’s hangars,” a senior Foreign Ministry official told The Times of Israel.
“Against all evidence, UNRWA refuses to acknowledge reality and pathetically attempts to ingratiate itself with Hamas, pretending that nothing serious has happened,” the senior official said. “This is a classic case of beaten-wife syndrome, which we have been witnessing for years from UNRWA. The people of Gaza, and indeed taxpayers from countries who contributive to UNRWA’s budget — including Israel — deserve better.”

And now another incidence:


And "surprising" further developments as of July 24, 2014:

The UN secretary-general on Wednesday said he was “alarmed” to hear that rockets were placed in a UN-run school in Gaza and now “have gone missing,” and he demanded a full review of such incidents

For full report see:

http://www.timesofisrael.com/rockets-found-at-un-gaza-school-have-gone-missing/