Iran fired a new wave of missile attacks on Israel early Monday, triggering air raid sirens across the country as emergency services reported at least five killed and dozens more wounded in the fourth day of open warfare between the regional foes that showed no sign of slowing.

Israel and Iran kept up their attacks, killing and wounding civilians and raising concern among world leaders meeting in Canada this week that the biggest battle between the two old enemies could lead to a broader regional conflict.

Dozens of others were injured overnight across Israel, the authorities said. Israel was striking military sites in Iran and the four-day-old conflict showed no sign of slowing.

Israeli citizens were ordered to head to bomb shelters on Friday night amid retaliatory missile strikes from Iran.