GAZA CITY, Gaza Strip — Officials say Israel and Hamas militants have exchanged fire in the most serious flare-up in months on the Jewish state's border with the Gaza Strip.

An Israeli army spokeswoman says Palestinian militants fired around 30 rockets on Monday. Gaza's Interior Ministry says Israel's military launched around 20 missiles, mostly toward targets in the southern Gaza city of Khan Younis.

Palestinian health official Ashraf al-Kidra says that five people were injured.

The exchange of fire began after Israel launched an airstrike into southern Gaza on Sunday night targeting two men, killing one. Israel says they were militant jihadists responsible for attacks.

Gaza's militant Hamas rulers have not confirmed the targeted men's identity.