Shenzhen Seismological Bureau claims that toads taking to the streets is a normal phenomenon during the breeding season. Two days before the "5·；12" earthquake, a large number of toads in Mianzhu, Sichuan were found to migrate, which aroused discussion and speculation about pre-earthquake omens in all sectors of society. Shenzhen held a 2008 annual air-raid siren test from 11:00 am to 11:15 on September 7, with synchronized sirens throughout the city.