Gaza City, Gaza Strip ? The eight-month closure of Gaza has created “grim and miserable” conditions that deprive Palestinians of their basic dignity, the U.N.’s humanitarian chief said Friday.

Later Friday, a powerful blast went off in the house of a senior Islamic Jihad activist, killing him, his wife and daughter, and three neighbors, medics and an Islamic Jihad spokesman said. Islamic Jihad said an Israeli airstrike targeted the house, but Israel denied it.

John Holmes, undersecretary-general for humanitarian affairs, visited Gaza during the day and urged that the territory’s borders be reopened to relieve the suffering.

Israel and Egypt severely restricted access to Gaza after the Islamic militant group Hamas seized the territory by force in June. Since then, only a few dozen trucks carrying food, medicine and other staples have been permitted into Gaza every day, while most exports are banned.

“All this makes for a grim human and humanitarian situation here in Gaza, which means that people are not able to live with the basic dignity to which they are entitled,” Holmes told reporters in Gaza.

The extent of suffering in Gaza has been a subject of dispute. Palestinians and human rights groups say hardship is widespread, while Israeli government officials have accused Hamas of trying to manufacture a humanitarian crisis for political gain.

Holmes called for reopening Gaza, and said he would talk about it with Israeli officials and representatives of the West Bank government of moderate Palestinian President Mahmoud Abbas, Hamas’ rival.

“I have been shocked by the grim and miserable things I have seen and heard about during the day,” Holmes said.