Police arrested a 63-year-old man armed with a vehicle full of explosives outside of a crowded Detroit mosque last week, Michigan authorities revealed Sunday. The suspect, from Southern California, is believed to have acted alone but is being taken “very seriously,” police say. They also said he has a history of anti-government activity. The man’s car, parked outside of the Islamic Center of America in the Detroit suburb of Dearborn, was allegedly full of a large quantity of fireworks and M-80s, which are illegal in Michigan. The Arab-American community where the incident occurred is one of the largest in the U.S.