GAZA, Aug 5 (Reuters) - Palestinian militants in Gaza fired dozens of rockets into Israel on Friday in response to Israeli airstrikes which killed at least 5 people, including a senior commander of the Palestinian Islamic Jihad movement.

As darkness fell, Israeli authorities said sirens had been sounded in southern and central areas, while images broadcast by Israeli television stations appeared to show a number of missiles being shot down by air defence systems. In Tel Aviv, Israel's economic centre, witnesses said they could hear booms but there were no reports of sirens 

militant group in a wave of strikes Friday that Israel said were meant to prevent an imminent attack. A 5-year-old girl and two women are among those killed in the strikes.

So far, Hamas, the larger militant group that rules Gaza, appeared to stay on the sidelines of the conflict, keeping its intensity somewhat contained. Israel and Hamas fought a war barely a year ago, one of four major conflicts and several smaller battles over the last 15 years that wreaked a staggering cost to the impoverished territory's 2 million Palestinian residents.