Old Saybrook - School and police officials are taking extra precautions this morning at the Old Saybrook High School after a bomb threat was found written on a bathroom wall.

In a letter sent out to parents Wednesday, the threat was found last week and made reference to May 17.

The school’s administration and school resource officer have conducted a joint investigation and found no credible threat against the building or students, the letter said.

As a precaution, teachers secured their classrooms Thursday after dismissal and no students or staff were allowed in the building after 6 p.m.

Students were asked Friday to limit their use of bags and expect bag screenings.