Israel was struck by a surprise attack by Hamas early Saturday morning in one of the most serious escalations in years between Israel and the Islamist militant group. Israeli Prime Minister Benjamin Netanyahu declared the country was “at war.”

The massive assault combined a barrage of rockets fired from the Gaza Strip into Israel and dozens of heavily armed gunmen attacking the country’s south from Gaza. Some 200 Israelis have reportedly been wounded in the onslaught that hit towns and cities across the south and center of Israel in the early hours of Saturday.

“We are at war, and we will win,” Netanyahu said in a message to Israelis.

The Israel Defense Forces responded by striking Hamas targets in Gaza. “The IDF is initiating a large-scale operation to defend Israeli civilians against the combined attack launched against Israel by Hamas this morning,” the IDF said in a statement.

IDF spokesman Rear Adm. Daniel Hagari told reporters that more than 2,200 rockets have been fired into Israel Saturday morning, the Times of Israel reported. Hagari said the Hamas militants infiltrated from land, sea and air.

Israel’s Defense Minister Yoav Gallant warned that Hamas “made a grave mistake,” the Associated Press reported. He spoke following a security cabinet meeting at the Israeli military headquarters in Tel Aviv Saturday.

Pictures and videos on social media suggest that several civilians may have been injured or killed during an attack on the southern Israeli town of Sderot, at the border with the Gaza Strip. Those images appear to show uniformed Palestinian gunmen opening fire on civilians and civilian vehicles on the streets.

“Hamas … which is behind this attack, will bear the results and responsibility for the events,” the armed forces said in a statement.

Amid reports of widespread infiltration of Hamas fighters, Israeli Defense Minister Yoav Gallant announced he had given the green light for army reservists to be called up for active service. The middle eastern nation’s defense forces are heavily reliant on 465,000 eligible part-time soldiers, and the number called up will depend on how the situation unfolds, Gallant said.

Mohammed Deif, the de facto leader of the Gaza headquartered Hamas group, issued a recorded message prior to the attacks, declaring the start of “Operation Al-Aqsa Storm” — a reference to the symbolic mosque that stands on Temple Mount in East Jerusalem.

“Enough is enough,” he said, calling on Palestinians to take up arms against Israel.

Seth Franzman, a regional political analyst in Jerusalem, told POLITICO that he and his family had been “woken up by sirens and rocket fire at around 8 in the morning.” He added: “We could see the explosions from our balcony. My family’s in the shelter now because, even though Israel has advanced air defenses, things can fall out of the sky when they’re intercepted.”

“This is a pretty major surprise attack,” said Franzman, who also works as an editor for The Jerusalem Post, “because there wasn’t the usual back and forth drumbeat between Israel and Hamas that takes place before escalations. This is totally different.”

The EU condemned the attacks. “I unequivocally condemn the attack carried out by Hamas terrorists against Israel,” European Commission President Ursula Von der Leyen said in a statement. “It is terrorism in its most despicable form.”

“Israel has the right to defend itself against such heinous attacks,” she said.

“This horrific violence must stop immediately. Terrorism and violence solve nothing,” Josep Borrell, the bloc’s top diplomat, said in a statement. “The EU expresses its solidarity with Israel in these difficult moments.”