An air raid siren rang out across the capital on Wednesday, catching residents off guard and sparking a mixture of fear, indifference and uncertainty. A technical fault was to blame for the false alarm, the Home Front Command said, adding that a thorough investigation was underway. Emergency hotlines were flooded by calls from worried residents, with Magen David Adom reporting more than 200 inquiries from people seeking instructions on what to do. The sirens in Jerusalem sounded just before 1 p.m., at the same time that sirens were also heard in Yavne. Some reports speculated that the rocket alert system reacted in an oversensitive manner to a projectile fired in Jerusalem's general direction, but which fell far short of the capital. Children at the Pri Megadim Elementary School in Ma'aleh Adumim, east of the capital, were herded into bomb shelters. "Some of the students were upset and crying," second-grader Matan, 8, recounted. "But I knew it was OK because I saw that the teachers were calm." Hundreds of startled residents of called Magen David Adom's emergency number after hearing the siren. MDA personnel calmed them down after quickly learning that the siren sounded as an error. Additional personnel were put on the job to answer phone calls and advise callers to disregard the siren. Col. Anwar Sa'ab, head of the Home Front Command's Central District, told The Jerusalem Post thanks to the error that triggered the siren, Jerusalem had an opportunity to test its responses to a rocket attack. "It's true that not everyone took it seriously, but this siren was a drill for the city. It put Jerusalem in a state of readiness. In schools, we saw correct responses, with children led into bomb shelters," Sa'ab said. Two rockets hit in Sa'ab's Central District on Thursday. He said his region was fully prepared. "In our district we have made excellent preparations. We distributed clear instructions to residents telling them to clean out their safe rooms, and we are working with local councils to ensure that public bomb shelters are ready. Our preparations were very organized and aimed at getting civilians to understand the importance of the siren and of reaming alert," Sa'ab said. Towns like Yavne and Gedera were prepared in terms of bomb shelters, Sa'ad added, while cities that had not been targeted and are considered out of rocket range, such as Rehovot, Ness Ziona and Rishon Lezion, have seen a lower level of preparation. Chances were low that such cities would be struck by rockets, he said. "We met with the heads of those cities to discuss how to respond if and when something happens." The Home Front Command was not overly concerned by reports of a phosphorous mortar attack on the Eshkol region on Wednesday, Sa'ab said, adding that the mortar shell did not represent a dramatically higher level of threat. Judy Siegel contributed to this report.