6:30 AM ET: CNN is reporting that officials are worried that the suspect who remains at large could have explosives on his body. An official tells the network that the suspect killed overnight had explosives on his body.  As a result, city officials have suspended all public transportation for the time being. Those in Watertown and the surrounding neighborhoods are being urged to shelter in place until further notice. Many colleges have cancelled classes for the day.  Businesses are being told not to open.