Israeli aircraft hit more than 70 targets in Gaza

On arriving in Cairo, Kerry announced the U.S. will send $47 million in humanitarian aid for tens of thousands of Palestinians who fled their homes in the coastal territory to escape the violence. Kerry's top aides warned, however, that achieving an immediate and lasting cease—fire would be difficult and he hoped to make any progress over the next several days to secure even a temporary pause in the bloodshed.

It's not clear exactly what Israel and Hamas would each demand in return for agreeing to a truce now, but senior State Department officials said the issue of opening border crossings potentially into Israel and Egypt was under discussion.

“We will work to see if there is some way to not only arrive at a cease—fire of some kind but to get to a discussion about the underlying issues,” Kerry said at the start of his meeting with Ban. “Nothing will be resolved by any cease—fire, temporary or long, without really getting to those issues at some point and that's what we need to do.”

Kerry remained in Cairo on Monday for more meetings with top Egyptian officials. But there were no immediate plans for face—to—face meetings with officials from Qatar, Turkey, Israel and the West Bank.