It was for the most part business as usual at the Knesset on Tuesday, despite the air raid sirens that blasted through the building at 11 a.m., but the continuation of debates in the committee rooms was not due to apathy, but rather to the fact that the building's committee rooms are all considered safe zones. The windowless plenum hall is also considered a safe zone, but is kept locked as a security procedure when the plenum is not underway. It was this precaution that stymied Knesset director-general Dan Landau, who ran first to the plenum during Tuesday's drill, only to find the doors locked. Landau was redirected to a nearby safe room where Knesset Speaker Reuven Rivlin and his entourage were also taking cover. Meanwhile, visitors, employees and MKs who were not in committee rooms were escorted to safe zones by Knesset guards. The expansive building has literally dozens of defined areas, including interior hallways and rooms - most of which sprouted colorful signs indicating "safe area" in the days leading up to the drill. Other members of the Knesset guard simulated of a situation in which a member of Knesset or minister did not reach a secure area and was wounded by a missile. The threat, said Rivlin, was not merely theoretical. In a conversation with reporters, the speaker said that especially since the assassination of terror mastermind Imad Mugniyeh, the Knesset was considered to be high on the list for terrorists who would like to attack prominent Israeli symbols and institutions. But within minutes of the siren, the parliament returned to business as usual, with MKs meeting - perhaps with a new understanding of what southern constituents faced on a daily basis - to discuss, among other topics, building secure areas within Ashkelon's Barzilai Hospital, where sirens are all too frequently more than just a drill.