The city of Baltimore has closed its public schools Tuesday following the violent protests over the death of Freddie Gray that continued late into Monday night. Suburban schools in Montgomery, Prince George's and Anne Arundel Counties have also canceled their field trips into the city. Baltimore County sent an email to staff Monday alerting that field trips would be canceled or delayed through the week and possibly longer. All Catholic schools in Baltimore City were also closed Tuesday, with the exception of School of the Cathedral. Elsewhere Johns Hopkins University sent an alert to students urging them to seek shelter on the Baltimore campus due to the nearby unrest.