US Embassy in Israel Warns Americans to Stay ‘Vigilant’ After Surprise Hamas Attack

The U.S. Embassy in Jerusalem urged citizens to "remain vigilant" Saturday as personnel hunkered down after a surprise Hamas rocket strike on Israel left at least 22 people dead and Israel at war.

"The U.S. Embassy is closely monitoring the security situation as a result of rockets fired from Gaza across southern and central Israel, including Tel Aviv and Jerusalem, and the infiltration of Hamas militants," the embassy said in a security alert.

"The U.S. Embassy is aware that there have been casualties as a result of these incidents," the alert continued. "U.S. citizens are reminded to remain vigilant and take appropriate steps to increase their security awareness as security incidents, including mortar and rocket fire, often take place without warning. "

Embassy personnel were "sheltering in place," the alert said.

In an attack of unprecedented scale, Hamas launched thousands of rockets at Israel on Saturday, leaving at least 22 people dead and police pressed into service alongside Israeli troops as fighting continued.

After the strikes, Israeli Prime Minister Benjamin Netanyahu gave a televised address in which he declared the nation "at war."