JERUSALEM — Palestinian deaths from Israel’s aerial attacks in Gaza rose sharply on Thursday, while militants there fired more than 180 rockets into Israel, reaching new targets spread across a vast area of the country.

The escalation appeared to increase the likelihood of a ground invasion and prompted the United Nations secretary general, Ban Ki-moon, to call urgently for a return to calm and a cease-fire.

“Today, we face the risk of an all-out escalation in Israel and Gaza, with the threat of a ground offensive still palpable — and preventable only if Hamas stops rocket firing,” he told an emergency meeting of the Security Council. There were no signs that a cease-fire was imminent, and no signs that diplomats representing the antagonists were heeding Mr. Ban’s call for calm.

Ron Prosor, Israel’s ambassador to the United Nations, played an air-raid siren at the Council meeting to reflect what his country’s citizens hear every day. He called his Palestinian counterpart, Riyad Mansour, “a mouthpiece of Hamas.” Mr. Mansour blamed the underlying Israeli occupation, exhorting the Council to intervene and “salvage prospects for peace and security.”