Israeli strikes killed at least three Palestinians in Gaza on Sunday, including two members of the Hamas-run police force, health officials said, in violence that highlighted the fragility of a U.S.-brokered cease-fire.

Medics said one person was killed and two others were wounded in an Israeli airstrike on the Maghazi refugee camp in central Gaza.

The Israeli military said it targeted two individuals who were carrying out “suspicious” activity and moving toward its forces, posing what it described as an immediate threat.

In a separate strike on Sunday, Gaza’s Hamas-run interior ministry said the head of the police force in Khan Younis, Wessam Abdel-Hadi, and his aide were killed.

The Israeli military said it struck Hamas members in the southern Gaza Strip, whom they alleged were operating to “advance imminent attacks” against Israeli forces.