Residents of southern Israel suffered another day under siege on Sunday as Palestinians in the Gaza Strip fired about 50 more rockets at the Negev.

Two Grad-type Katyusha rockets fell in Be'er Sheva after the Iron Dome battery that had been protecting it suffered a technical malfunction.

One rocket hit a school, which was empty since schools in the city were closed on Sunday, and the other hit a parked car. Fifteen people were treated for shock, though there were no other casualties. The rockets - and the ball bearings that they ejected hundreds of meters - caused heavy damage to buildings and vehicles.

Another rocket hit a chicken coop in Moshav Carmia in the Ashkelon Coast Regional Council, causing heavy damage.

The Israel Air Force made 16 sorties over Gaza to destroy rocket launchers. Palestinian sources said that three Gazans were killed, among them a 13-year-old boy, bringing the total number of Palestinian casualties in this round of hostilities to 18.

Some 200,000 pupils will remain at home again on Monday, as schools remain closed in Be'er Sheva, Ofakim, Ashdod, Yavneh, Ashkelon, Kiryat Malakhi and Netivot, and in all the other smaller communities that are between seven and 40 kilometers from the Gaza Strip.

"All day we have to sit in the shelters and wait under tension. This is an insufferable situation," said Roni, a Be'er Sheva resident. "I don't understand how the government lets this happen. This is a catastrophe that can't continue."

Be'er Sheva Mayor Ruvik Danilovich said that he had spoken to Defense Minister Ehud Barak, "and I updated him on the people's mood. I asked him to work decisively to bring back quiet to the south. I made it clear that we cannot agree that this should be part of our routine."

Col. Tzvika Haimovich, commander of the IAF's active defense wing, told Haaretz that, regrettably, the Iron Dome battery protecting Be'er Sheva suffered a malfunction just as rockets had been launched. The air force is investigating what caused the malfunction, he said.

Before the malfunction, the batteries deployed near Ashkelon, Ashdod and Be'er Sheva successfully shot down 13 of the 15 rockets aimed at those cities on Sunday.

Overall, the system has been scoring impressive interception rates. According to Israel Defense Forces statistics, during this latest escalation the system intercepted 40 of the 49 rockets identified as destined to fall in populated areas.

"We follow up on every incident, whether a rocket was intercepted or not," said Haimovich. "We will do the best we can to succeed ... but it would be irresponsible and unprofessional to say there can be total protection."

Following a situation assessment by Barak, Chief of General Staff Lt. Gen. Benny Gantz, and Shin Bet security service head Yoram Cohen, the security establishment listed several achievements: hits on senior members of the Popular Resistance Committees, although its men continued to fire rockets at Israel; casualties inflicted on Islamic Jihad operatives, particularly those who fired rockets at Israel; and the success of the active defense apparatus.

Barak said he plans to have the Iron Dome anti-rocket defense system declared a "national emergency project," so as to expedite the manufacture and deployment of additional batteries. A fourth Iron Dome battery is being prepared for deployment and is expected to be operational within weeks.

Barak, however, warned on Sunday that "the current escalation is liable to be lengthy." Gantz, at a change-of-command ceremony for the Central Command, said, "The IDF responded and will continue to respond with strength and determination to all fire at the State of Israel's sovereign territory."

Gantz said Israel had no interest in escalation for its own sake, and declared Hamas responsible for all activity in the Gaza Strip.

The IDF also pointed a figure at Iran for supporting and financing the Islamic Jihad. While efforts to secure a cease-fire continue, the army reiterated that "as long as there's shooting, the decision is to continue to operate and hit whatever we can."

Prime Minister Benjamin Netanyahu met with southern mayors on Sunday in Ashdod, where several of them asked him to launch a military operation in Gaza in response to the rocket fire.

"The winning combination is the ability to attack, the ability to defend, and civilian resilience," Netanyahu said.