Hamas authorities arrested a number of people suspected of torching a UN-run summer camp in Gaza City earlier this week, the interior ministry of deposed Hamas government announced Tuesday.

The suspects are being interrogated, a statement sent to reporters by the ministry said.

There has been no more information about the number of the detainees or the group they are affiliated to.

Ihab Al-Ghussein, the ministry's spokesman, told Xinhua that he can't reveal more before the questioning is over.

Early on Sunday, an under-constructed beachside summer camp, run by the UN Relief and Works Agency (UNRWA), was vandalized.

Sources from the agency, which cares for Palestinian refugees, said more than 20 gunmen attacked the place at dawn, burned empty water tanks and cut the plastic surroundings of the camp after handcuffing a guard.

An envelop carrying a letter of threat to the UNRWA operations director John Ging and three bullets were tucked into the guard's coat, the sources said.

Meanwhile, Adnan Abu Hassna, a UNRWA spokesman, welcomed the arrest of the alleged perpetrators and said the agency has not yet been informed of the interrogation process.

"This is a very positive procedure, which proves the investigation is carried out with seriousness," Abu Hassna told Xinhua.

He added the investigation which the Hamas interior ministry has conducted "creates good atmosphere for the "UNRWA summer games program" which is to start next month.