Israel bombarded the Hamas-ruled Gaza Strip with about 300 airstrikes today and shot down a Palestinian rocket fired at Tel Aviv, the military said, widening a blistering assault to include the Hamas prime minister's headquarters, a police compound, and a vast network of smuggling tunnels. The Israeli attacks, which Gaza officials say left 12 dead, came as Palestinian militants fired more than 100 rockets toward Israel, including two aimed at the commercial and cultural center of Tel Aviv. Rocket attacks on Tel Aviv and Jerusalem this week mark the first time Gaza militants have managed to fire rockets toward the cities, raising the stakes in the confrontation.