At least 40 rockets were launched from the Gaza Strip into south Israel after 8 p.m. Monday evening, as the IDF prepared for a possible extensive operation in the Hamas-controlled coastal enclave. No injuries were reported.

Warning sirens were heard in the cities of Sderot, Netivot, Ofakim, and Rahat, as well as further afield in Rehovot, Gan Yavne, Gadera and Beit Shemesh, in the hills outside Jerusalem.

Media reports put the number of rockets launched at 70, but the IDF tallied “over 40 rockets” shot at Israel. The army said 12 rockets were shot down by the Iron Dome anti-missile system, including seven over Ashdod and five over Netivot.

The barrage came as residents in areas within 40 kilometers of Gaza, including Ashdod and Beersheba, were instructed by the IDF not to hold large gatherings and to stay near bomb shelters, and ministers reportedly warned of rocket strikes as far as the Tel Aviv region.

Sirens were heard at the same time in the Jerusalem area, including Tekoa and Efrat, and in the center of the country as well, but no rocket strikes were confirmed in those areas.

The IDF’s Home Front Command instructed the municipalities of Ashkelon, Ashdod and Beersheba, as well as regional councils in vicinity of Gaza, to prepare public bomb shelters for opening. Residents in the south were also instructed not to attend gatherings of 500 people or more.

Earlier Monday, government officials decided to increase strikes against Hamas in Gaza and call up additional troops, as southern Israel braced for intensified rocket fire following the deaths of several terror operatives in Gaza overnight.

The decision came hours after the IDF launched an airstrike at “three concealed launchers” in the Gaza Strip Monday, after over 50 rockets hammered Israel’s south earlier throughout the day. The Israeli airstrike targeted the Beit Lahia and Jabalya areas in the northern end of the Strip, Israeli Radio reported.

According to the Palestinian Ma’an News Agency, a four-year-old Palestinian boy was moderately wounded in the attack.

IDF spokesman Lt. Col. Peter Lerner said the military had called up 1,500 reserves troops, mostly from the Home Front Command and Iron Dome air defense crews, and deployed two additional conscripted infantry brigades, Paratroops and Givati, to the border with the Palestinian enclave Monday. The army, Lerner said, was still in a defensive position but has shifted its readiness in order to address an escalation in the ongoing conflict with the Gaza Strip.

Israeli soldiers stand next to Merkava tanks positioned on the Israeli side of the border with the Gaza Strip on July 7, 2014. ( photo credit: AFP/JACK GUEZ)

Israeli soldiers stand next to Merkava tanks positioned on the Israeli side of the border with the Gaza Strip on July 7, 2014. ( photo credit: AFP/JACK GUEZ)

On Monday afternoon, senior ministers in Israel’s security cabinet voted to instruct the IDF to increase air raids against targets in Gaza, following a meeting in Jerusalem.

Though the security cabinet did not decide on a ground incursion or large scale operation, they warned one could be in the offing if rocket fire did not cease, Israeli media reported.

The decision followed the death of some six Hamas members overnight, in what the military said was a “work accident,” when an explosive-laden tunnel that was hit in an Israeli airstrike several days earlier exploded.

Three other terror operatives were reported killed in other Israeli strikes.

Ministers warned that the increase in violence could bring rocket fire to the Gush Dan region of central Israel, news site NRG reported. The area, which includes the heavily populated cities of Tel Aviv and Rishon Lezion, last saw rocket fire in 2012 during Operation Pillar of Defense.

Israelis have been gearing up for a possible escalation for several weeks, amid a marked uptick in rocket fire following an Israeli crackdown on Hamas in the wake of the abduction and killing of three Israeli teens in the West Bank last month.

Military officials say about 200 rockets have been fired at southern Israel since the start of the operation.

Tensions have also ratcheted up following the killing of an Arab teen in Jerusalem by suspected Jewish extremists in an apparent revenge attack last week, leading to riots in the capital and several Arab towns.

Earlier Monday, a Hamas official said it would not agree to a ceasefire unless detainees arrested in the crackdown were released. The group also released a video calling on “settlers” in the southern Israeli town of Beersheba to “flee before it is too late.”

On Saturday night, Hamas warned it could hit any Israeli city with its missiles.