At least three rockets fired from Lebanon hit northern Israel on Thursday morning, raising fears that a second front could open up with Hizbollah, the Lebanese Shia group, when Israeli troops are engaged in a massive offensive in the Gaza Strip.

It was not clear, however, whether it was the Shia group that fired the rockets, which left three Israeli civilians lightly injured. Lebanon said it was trying to determine who fired the rockets, and that it was committed to the truce with Israel.