Masked gunmen in the Gaza Strip have set fire to a United Nations-run summer camp for children.
This follows a similar attack in May on another UN-run summer camp.
Some militants view the UN as a symbol of the West and claim that the summer camps allow boys and girls to mix freely - something that the UN denies.
The attackers tied up the guard at the camp in central Gaza before setting fire to chairs, tables, easels and other equipment.
The UN says about 25 armed men attacked the beach camp in the middle of Sunday night.
Nobody was hurt, and nobody has claimed responsibility for the attack.
But in a similar incident last month a previously unknown Islamist group said its had attacked a UN summer camp in Gaza city.
The head in Gaza of the UN Relief and Works Agency (UNRWA) for Palestinian refugees condemned the attack as "cowardly and despicable".
"This is another example of the growing levels of extremism in Gaza and further evidence, if that were needed, of the urgency to change the circumstances on the ground," John Ging said.
UNRWA said the camp would be repaired and promised to maintain its 1,200 summer camps, at which about 250,000 Gazan children take part in activities including sports, swimming, arts and theatre during the summer months.
Hamas, the Islamist movement that controls the Gaza, condemned the previous attack on 23 May.
Some in Gaza though believe that such attacks involving so many men could not be carried out with at least the complicit support of Hamas, BBC Gaza correspondent Jon Donnison reports.
Hamas also runs rival summer camps.
A spokesman for the Interior ministry in Gaza said it would catch whoever carried out last night's raid and that they would be jailed.