JERUSALEM - Palestinian militants in the Gaza Strip fired rockets at Israeli cities on Thursday, police said, in a second day of a cross-border flare-up.

Sirens sounded in the southern Israeli towns of Ashkelon and Ashdod. Police said the rockets had landed in open areas, causing no casualties.

The Israeli military carried out 29 air strikes and fired tank shells at militant targets in the Gaza Strip on Wednesday after the Islamic Jihad group launched 60 rockets toward Israel in the heaviest barrage in nearly two years.

No casualties were reported on either side of the frontier in Wednesday's incidents. Islamic Jihad said its rocket fire had been a response to Israel's killing of three of its men a day earlier.