Moroccan police have arrested a key suspect in the 2004 Madrid bombings and 2003 terrorist attacks in Casablanca, French media reported Friday. Saad Houssaini, a chemist and alleged member of the Moroccan Islamic Combatant Group, was arrested Thursday in Casablanca, RFI radio and LCI television reported. Moroccan police officials could not immediately confirm the reports. No other details were immediately available. On March 11, 2004, a group of mostly North African Muslim extremists blew up four Madrid commuter trains, killing 191 people and injuring more than 1,500. Currently 29 people are on trial for their alleged roles in the attacks, including 15 Moroccans.