Classes resumed at an elementary school in the city of Toyama on Tuesday amid tight security, a week after a man killed a security guard who worked at the school and a police officer, with a knife and a gun, as well as firing bullets at the school.

Pupils were accompanied by family members as they went to Okuda Elementary School after authorities requested that they be escorted, while teachers stood at nearby intersections and police officers patrolled the area.

"I am worried my son might have a flashback of the incident," said a 45-year-old woman, who walked her second-grader to school. "I am also worried about threatening emails," the mother said, referring to messages sent to local police and a major daily newspaper suggesting that the school could be the target of a new attack. The threats delayed the school's reopening, which had originally been scheduled for Monday.