A rocket fired from the Gaza Strip struck a house in southern Israel early on Friday, without causing any casualties, a police spokeswoman said. \"A rocket hit a house in the town of Sderot, causing damage to the roof. There were no casualties but a resident was hospitalised in a state of shock,\" said the spokeswoman, Luba Samri. Another rocket struck in the Ashkelon region without causing casualties or damage. A Salafist group claimed responsibility for firing the two rockets. They were the latest in a string of rockets fired from Gaza in the past week to have been claimed by the hardline Islamists. In retaliation for previous rocket fire, the Israeli air force carried out three strikes on training camps of Gaza\'s Hamas rulers on Monday night, without causing casualties. Despite an informal truce between Hamas and Israel, tensions flare periodically on the Gaza-Israel border, with Palestinian militants firing rockets into the Jewish state and the Israeli military launching retaliatory air strikes on the Palestinian territory. The last major flare-up was in June, when militants fired more than 150 rockets at southern Israel, wounding five people, and Israel hit back with air strikes which killed 15 Palestinians.