The fighting between Israel and Iran intensified overnight, as both nations kept up their attacks, killing civilians and raising concern among world leaders that the biggest battle between old enemies could lead to a broad regional conflict.

Saudi Arabia is also working behind the scenes to promote a ceasefire framework, a source told The Jerusalem Post.

The aircraft carrier USS Nimitz, one of the world’s largest warships, is reportedly headed to the Middle East to boost the US’ presence as Israel and Iran do battle.

The death toll grew Sunday as Israel and Iran exchanged missile attacks for a third consecutive day, with Israel warning that worse is to come. Israel targeted Iran’s Defense Ministry headquarters in Tehran and sites it alleged were associated with Iran’s nuclear program,