Militants fired a Kassam rocket from the Gaza Strip into the western Negev in another violation of a truce agreement. The rocket landed Thursday in an open field near the Gaza border town of Sderot, an Israeli army official said. There were no casualties. It was the sixth violation of the Egyptian-brokered truce between Israel and Hamas that took effect June 19. No one claimed responsibility for the attack. Israel said it will close its border crossings with Gaza on Friday in response, Ha’aretz reported. The crossings are generally closed from Friday afternoon to Sunday.