A sign indicates the intermediate alarm level "Bravo Plus" at the entrance of the Army Engineer and Signal School in Hoyo de Manzanares, near Madrid, on May 22, 2009 where soldiers have been quarantined after 11 of them fell ill with suspected cases of the swine flu virus. The 11 were isolated at a hospital while the students who had contact with them were quarantined at the military academy, the local municipality said in a statement.