Hamas announced Saturday morning that it launched a Kassam rocket from the Gaza Strip into Israel, the first attack for which the organization took responsibility, since it declared a truce with Israel 16 months ago. The group said that the attack was "only the beginning," and that the range of the Kassam attacks would grow. However, security officials stated that Hamas was also responsible for the recent strikes against Sderot. Following the announcement, security forces revealed they were aware of as many as 97 alerts of potential attacks against Israel. This was the largest amount of alerts that they have received in recent years. In response Inspector General Moshe Karadi raised police alert to the second highest level. Police forces were to be dispatched on Sunday to secure the borderline between Israeli and Palestinian borders, including the Jerusalem area. Forces were also to monitor crowded areas in and around cities. Magen David Adom likewise increased its alert level. Hamas' military wing on Friday said it would no longer honor its self-declared truce with Israel following an explosion of a shell on a Gaza beach that killed seven civilians - an incident they attributed to Israeli artillery shelling. "The earthquake in the Zionist towns will start again," said a leaflet distributed at a Hamas rally Friday night. "The resistance groups ... will choose the proper place and time for the tough, strong and unique response." Israel and the Palestinians declared the truce in February 2005. Hamas, which has killed scores of Israelis in suicide bombings, has largely abided by the cease-fire. PA Prime Minister Ismail Haniyeh, a top Hamas official, also condemned the IDF attacks. "What is going on is war crimes in the full meaning of the word," he said after visiting the hospital where the wounded were treated. He called for an end in recent Palestinian infighting. Palestinian Authority Chairman Mahmoud Abbas also condemned the "bloody massacre" and called on the international community, including the US, Europe and the Security Council, to intervene. Sami Abu Zuhri, a Hamas spokesman in Gaza, said the attack showed "the Zionist occupation insists on killing ... and does not distinguish between civilian children and freedom fighters." GOC Southern Command Maj. General Yoav Gallant said that it seemed that neither the IAF nor the navy was behind the artillery explosion. He said that the incident was unusual since the IDF had fired thousands of shells in the past and such an accident had never before occurred, but stressed the army's regret that civilians were hurt by what could have been an IDF mistake. "We regret any harm caused to innocent civilians," said Capt. Jacob Dallal, an IDF spokesman. He said Israel offered medical assistance, including evacuation to hospitals in Israel, to the wounded. Military sources said that the targeted killings and the anti-Kassam operations over the weekend were not a "change in IDF policy" but rather a continuation of the overall policy to strike and kill terrorists involved in anti-Israel terror attacks. "We are responding to the rocket fire and defending ourselves while doing what we can to thwart additional attacks," a military source explained. The IDF further said that it held PA responsible for everything that occurs in Gaza Strip, and that the PA leadership's inaction in preventing attacks against Israel was forcing a step-up in offensive action to thwart attacks and dismantle the infrastructure that supports Kassam launch cells. It added that it had noted a recent increase in Hamas involvement with rocket fire.