At least two Palestinian militants have been killed by an Israeli air strike in Gaza City, Palestinian officials say.
Mohammed Abu Shariya and Suhail Baqir, members of the al-Aqsa Martyrs' Brigades, were killed when a missile hit their car in the east of the city.
Two bystanders were also wounded by the air strike.
The Israeli military said it had targeted militants responsible for recent rocket attacks from the Gaza Strip on Israeli towns.
Acting Israeli Prime Minister Ehud Olmert had earlier pledged earlier on Tuesday to "strike anyone who tries to carry out terrorist activity" after an Israeli woman was stabbed to death on Sunday and a rocket strike from Gaza wounded a baby on Friday.
'Ball of fire'
One witness said he was driving about 200m behind the militants' car when the missile struck.
"A strong explosion went off in the car, in the upper part of car. The front windows of my car were smashed and the car was like a big ball of fire," Ahman Barhum told the Associated Press.
A spokesman for the al-Aqsa Martyrs' Brigades vowed revenge for the deaths of the men, one of whom was a commander and the other a more junior activist.
"This is an open battle, we are ready and determined to continue to the end," Abu Qussi said.
This is the fourth time in the past few days that the Israeli air force have struck in this way.