Israel’s military ordered the evacuation Saturday of a crowded part of Gaza designated as a humanitarian zone, saying it is planning an operation against Hamas militants in Khan Younis, including parts of Muwasi, a makeshift tent camp where thousands are seeking refuge.

The order comes in response to rocket fire that Israel says originates from the area. It’s the second evacuation issued in a week in an area designated for Palestinians fleeing other parts of Gaza. Many Palestinians have been uprooted multiple times in search of safety during Israel’s punishing air and ground campaign.