The Israeli military shot down an Iranian drone that infiltrated the country early Saturday and struck Iranian targets in Syria that launched it, in what the military called a “severe and irregular violation of Israeli sovereignty.”

According to the Associated Press, the military said its planes faced heavy anti-aircraft counter fire from Syria that forced Israeli pilots to abandon an F-16 jet that crashed in northern Israel. It said the pilots were injured and evacuated to a hospital. Sirens sounded in northern Israel as a result of massive Syrian fire.

Israeli military spokesman Jonathan Conricus told AP that Iran was “responsible for this severe violation of Israeli sovereignty.”

The military says it is “monitoring events and is fully prepared for further action.”

Syrian state TV quoted a military official saying Syrian air defenses hit more than one Israeli plane. The official said the Israeli raids hit a base in the country’s central area, and called it a “new aggression.”

Israel has been warning of late of increased Iranian involvement along its border in Syria and Lebanon, AP reported.

It fears Iran could use Syrian territory to stage attacks or create a land corridor from Iran to Lebanon that could allow it to transfer weapons more easily to Hezbollah, AP reported.

Israel has shot down several drones that previously tried to infiltrate its territory from Syria. The targeting of an Iranian site in response, however, marks an escalation in the Israeli retaliation. The military confirmed that the Syrian target — the unmanned aircraft’s launch components — was successfully destroyed. The military’s top military leaders were meeting to coordinate Israel’s continued response.

Israel’s chief military spokesman, Brig. Gen. Ronen Manelis, said Israel held Iran directly responsible for the incident.

“This is a serious Iranian attack on Israeli territory. Iran is dragging the region into an adventure in which it doesn’t know how it will end,” he said in a special statement. “Whoever is responsible for this incident is the one who will pay the price.”