Israel closed the Kerem Shalom humanitarian crossing into Gaza on Sunday after a rocket barrage was fired by Hamas, as weekend talks on a potential truce broke up inconclusively.

The status of the talks was unclear after the latest round in Cairo: Hamas officials said their negotiators had returned to Qatar to consult with the group’s political leadership. CIA Director William Burns was also leaving Cairo for consultations in Qatar, Reuters reported.

Israel and Hamas have been negotiating for weeks through mediators toward a potential truce that would include the release of hostages held in Gaza and of Palestinian prisoners held in Israel. At the same time, Israel has threatened to launch an operation in Rafah, where it says Hamas battalions remain intact, and where hundreds of thousands of Palestinian civilians are sheltering.