Israeli forces have struck one of the largest residential towers in Rafah in the southern Gaza Strip, residents said, stepping up pressure on the last area of the enclave it has not yet invaded and where more than a million displaced Palestinians are sheltering.

The 12-floor Burj al-Masri building, located some 500 metres (1,640 feet) from the border with Egypt, was damaged in the air raid early on Saturday morning.

Dozens of families were made homeless though no casualties were reported, according to residents. The Israeli military did not immediately respond to requests for comment on the incident.

One of the tower’s 300 residents told the Reuters news agency that Israel gave them a 30-minute warning to flee the building at night.

“People were startled, running down the stairs, some fell, it was chaos. People left their belongings and money,” said Mohammad al-Nabrees, adding that among those who tripped down the stairs during the panicked evacuation was a friend’s pregnant wife.

A Rafah-based official with the Fatah party, which dominates the Palestinian Authority that has limited self-rule in the occupied West Bank, said he feared that hitting the Rafah tower was a sign of an imminent Israeli invasion.

Five months into Israel’s unrelenting air and ground assault on Gaza, health authorities say nearly 31,000 Palestinians have been killed, more than 72,500 wounded and thousands more are likely under rubble.

The offensive has plunged the Palestinian territory, already reeling from a 17-year Israel-led blockade, into a humanitarian catastrophe. Much of it has been reduced to rubble and most of the 2.3 million population have been displaced, with the United Nations warning of disease and starvation.