Militant Islamists have been rounded up by police in the Moroccan city of Casablanca in connection with Friday night's series of bomb attacks. At least 30 people were arrested in a major security operation across the city. A focus of the investigation will be whether the attackers were connected to a local Islamic organisation, says the BBC's Sebastian Usher in Casablanca, quoting an interior ministry source. The Salafiyah Jihadiyah is suspected of having links to Osama Bin Laden's al-Qaeda network which is blamed for anti-Western terror attacks around the world, he adds. At least 41 people were killed and about 100 more injured in the five blasts which hit Casablanca within 30 minutes of each other.