Israeli strikes on a tent camp in an evacuation area west of Rafah killed at least 21 on Tuesday, Gaza health authorities said, and tanks advanced to the centre of the southern Gaza city for the first time after a night of heavy bombardment.

Two days after an Israeli airstrike on another camp stirred global condemnation, Gaza emergency services said four tank shells hit a cluster of tents in Al-Mawasi, a coastal area that Israel had advised civilians in Rafah to move to for safety.

At least 12 of the dead were women, according to medical officials in the Hamas militant-run Palestinian enclave. An Israeli military spokesperson said: “As of this time, we are not aware of this incident.”

In central Rafah, tanks and armoured vehicles mounted with machineguns were spotted near Al-Awda mosque, witnesses told Reuters. The Israeli military said its forces continued to operate in the Rafah area, without commenting on reported advances into the city centre.

International unease over Israel’s three-week-old Rafah offensive has turned to outrage after an attack on Sunday set off a blaze in a tent camp in a western district of the city, killing at least 45 people. Israel said it had targeted Hamas commanders and had not intended to cause civilian casualties.

Global leaders voiced horror at the fire in a designated “humanitarian zone” of Rafah where families uprooted by fighting elsewhere had sought shelter, and urged the implementation of a World Court order last week for a halt to Israel’s assault.

Tuesday’s attack occurred in an area designated by Israel as an expanded humanitarian zone, to which it had called on civilians in Rafah to evacuate for their own safety when it launched its incursion in early May.

In a diplomatic move purportedly aimed at reining in the violence, Spain, Ireland and Norway were to officially recognise a Palestinian state on Tuesday.

Also read: Spain to recognise Palestinian state with East Jerusalem as capital

The three countries have said they hope their decision will accelerate efforts towards securing a ceasefire in Israel’s war against Hamas militants, now in its eighth month, that has reduced much of the densely populated territory to rubble.

Residents said Rafah’s Tel Al-Sultan neighbourhood, the scene of Sunday’s night-time strike in which tents and shelters were set ablaze as families settled down to sleep, was still being bombarded.

“Tank shells are falling everywhere in Tel Al-Sultan. Many families have fled their houses in western Rafah under fire throughout the night,” one resident told Reuters via a chat app.

Around one million people - many repeatedly displaced by shifting waves of the war - have fled the Israeli offensive in Rafah since early May, the U.N. agency for Palestinian refugees (UNRWA) reported on Tuesday.

A video obtained by Reuters showed families on the move again, carrying their belongings through Rafah’s shattered streets, their weary children trailing behind them.

“There are a lot of attacks, smoke and dust. It is death from God…The (Israelis) are hitting everywhere. We’re tired,” said Moayad Fusaifas, pushing along belongings on two bicycles.