Israel was plunged into chaos Saturday after the Palestinian militant group Hamas launched a deadly land, air and sea attack inside the country, with fighters infiltrating the southern border and firing a massive barrage of rockets from the Gaza Strip.

"We are in a war," Israeli Prime Minister Benjamin Netanyahu declared in a video on social media. He ordered strikes on Gaza and called for an "extensive reserve mobilization" as the nation responds to the unprecedented incursion.

At least 70 people in Israel have been killed, a spokesperson for the Israeli rescue service Magen David Adom said in a statement.

Graphic but unverified video and photos shared on social media suggested that toll could rise sharply, while Hamas fighters were able to take a number of soldiers and civilians hostage, the Israeli military said.

Gaza's health ministry said 198 people were killed after Israeli airstrikes there, with another 1,610 injured.