At least 13 Palestinians, including three commanders of the militant group Islamic Jihad, have been killed in Israeli air strikes on the Gaza Strip.
A Palestinian health official said six women and four children were among the dead. Another 20 people were injured.
Israel said it had launched an operation targeting militants who posed an imminent threat to its citizens.
Islamic Jihad has vowed revenge and Gaza-based militants are expected to respond with rocket fire into Israel.