Portland, Maine's superintendent says security is being heightened after four black students reported that a white teenager made a racist remark toward them and waved a knife.

According to The Portland Press Herald, Xavier Botana told parents in a letter Sunday (Jan. 29) evening that the Casco Bay High School students are "physically fine." The school will help them with any emotional or psychological wounds.

The incident happened on Friday afternoon as the teens waited for a bus.

The ninth-graders say three teens walked by and one made a racial comment. A verbal confrontation ensued. They say one youth assaulted two of the students, pulled out a knife and fled.

Botana says police are boosting their presence near school buildings. School officials will also weigh further security measures.

No arrests have been made.

[Source: AP, Press Herald]