Jerusalem ? Israel threatened retaliation Saturday after two brothers, ages 8 and 19, were seriously wounded when a rocket from Gaza slammed into the center of the Israeli border town of Sderot.

The ongoing rocket fire from the Gaza Strip and Israeli military attacks could hamper the Bush administration’s efforts to prod Israel and the Palestinians toward a final peace agreement by the end of the year.

“Israel will take resolute and decisive measures to protect our citizens,” government spokesman David Baker said. “We will not allow Israeli families to be victimized by Palestinian rockets in the heart of their own cities.”

The rocket was one of 11 fired toward southern Israel on Saturday, police said. It landed yards away from a road where a family was running to seek shelter as warning sirens rang out to announce the attack, Israeli media reported.