Four people are in custody following a deadly knife attack in eastern France that is believed to be linked to Islamic extremism. The suspect, a 37-year-old Algerian man, had a conviction for glorifying terrorism and is described as an Islamic extremist with a schizophrenic profile. The attack occurred at a market in Mulhouse, resulting in the death of a civilian and injuries to seven police officers. The French government plans to address immigration in response to the incident.