Hezbollah and Israel exchanged heavy fire into Sunday, as the Lebanese militant group sent rockets deep into northern Israeli territory after facing some of the most intense bombardment in almost a year of conflict.

Hezbollah fired over 100 rockets early Sunday across northern Israel, with some landing near the city of Haifa, as Israel launched hundreds of strikes on Lebanon. A Hezbollah leader declared an “open-ended battle” was underway as both sides appeared to be spiraling closer toward all-out war.

Tensions between Israel and Hezbollah rose sharply in recent days, after an Israeli airstrike killed a senior Hezbollah official. On Sunday, Hezbollah fired more than 150 rockets at Israel, damaging homes and sparking fires.