Not long after the single-tone siren went off Friday announcing the beginning of Shabbat, another very different sounding siren was heard throughout the capital and its suburbs.Hamas fired a projectile from Gaza toward Jerusalem, breaking a long-standing taboo on the city that is home to some of Islam’s holiest sites as well as a large Palestinian and Israeli-Arab population. The rocket exploded near a Palestinian village in the West Bank, shattering windows.The rocket, called the M-75 by Hamas, triggered air raid sirens in the capital for the first time in decades. It was the first time warning sirens were heard in Jerusalem since the First Gulf War in 1991, but even then, Iraq’s leader Saddam Hussein refrained from targeting the city.In Ma’aleh Adumim, the siren shattered the Shabbat eve calm. In our house, our family exchanged quizzical looks for a couple of seconds, until we realized what the siren actually was. Not having a reinforced room in our home, we considered running out to the other side of our building, which houses the shelter. According to the IDF Home Front Command, residents in the Jerusalem area have 90 seconds to reach safe shelter. So, in the end, we instead decided to go into the utility room in the back of our house.A few minutes after the siren’s end, we emerged, and things seemed surprisingly normal. I left to attend the Kabbalat Shabbat services that the egalitarian havura I belong to holds in the city’s community center, unsure whether anyone would show up. A full contingent arrived, and we spent the first few minutes exchanging our siren stories and expressing hope that it wouldn’t repeat itself.Meanwhile, Jerusalem Mayor Nir Barkat held a municipal situation assessment on Saturday night, with representatives of all security and rescue services in the city.Schools will operate in Jerusalem normally on Sunday.During a rocket alert, the light rail will continue traveling to the nearest station, where passengers will be allowed to get off the train and seek shelter.The municipality’s hotline, 106, will be open for residents’ questions, as well as the IDF Home Front Command's hotline, 1027.By Saturday night, life had resumed as if there hadn’t been a rocket launched at Jerusalem.At the Rav Chen theater in Talpiot, the 7 p.m. screening of the new James Bond movie Skyfall was packed with patrons, who may have been temporarily shaken, but more stirred by the action film than by the threat of a Hamas rocket.Jerusalem Post staff contributed to this report.