A senior health official in Gaza says hundreds of people have been trapped inside a hospital in the territory, hours after Israeli forces launched an attack on the facility and imposed a siege on it.

Ashraf al-Qudra, a spokesman for Gaza’s health ministry, said on Monday that some 700 patients along with staff at the Indonesian Hospital were under constant Israeli fire.

The hospital, which is funded by Jakarta and is located in the northeast Gaza town of Beit Lahia, came under attack by Israeli forces earlier in the day. At least 12 people were killed in the attack and dozens more were injured.

Israeli tanks have now encircled the complex under the pretext that it is being used by Palestinian resistance fighters.

The Israelis had used the same pretext to besiege Gaza’s largest hospital, al-Shifa, last week. However, the regime has yet to provide evidence that al-Shifa was a base for Palestinian fighters days after its forces entered the hospital by force.

Backed by the United States and several Western countries, Israel has defied widespread global condemnations of its attacks on hospitals, mosques, churches and schools in Gaza by launching repeated assaults on places of gathering where civilians seek shelter from the regime’s relentless bombardments.

The head of the World Health Organization (WHO), Tedros Adhanom Ghebreyesus, said on Monday that he was “appalled” by the attack on the Indonesian Hospital in Gaza.

Medical charity Medecins Sans Frontieres also said on Monday that the Israelis had attacked its clinic in Gaza City earlier in the day.

Gaza’s health ministry says that more than 13,000 people have been killed in 45 days of Israeli aggression on Gaza as of Monday.