East Lyme — Following an arrest in connection with an anonymous threat posted on the social media, the superintendent of schools updated the community in a letter saying that all schools will be open Monday and activities will proceed with additional security.

“While the police assure us that they no longer believe that a threat exists, we are providing additional security to ensure a sense of safety after a week of concerns,” Superintendent James Lombardo wrote in the email on Friday. “Police officers will be present at each school site, including the Coastal Connections program, beginning well before school begins until the end of the school day.”

“Also, we will institute additional security procedures in the coming days intended to ensure a safe and secure return for all our students and staff,” he added. “These procedures will remain in effect as long as we feel necessary.”

Lombardo said counselors will be available to talk with students, and teachers “will be vigilant to any issues students may raise during the school day.”

Additional security will also be provided this weekend at the women’s basketball game against Waterford High School this evening and the Southeastern Connecticut Chinese School on Sunday, he said.

Police arrested a former student, Tyler McKenzie, 18, on Wednesday in connection with a post on Yik Yak, an anonymous online application. The post stated: “East Lyme better get ready for the hail of bullets I’ve been bullied to [sic] long and after break I’m going to let all my anger out.”

In reference to news reports that cited bullying as a “possible motivation” to the posting, Lombardo also updated the community on the schools’ anti-bullying policy, which he said is outlined on the schools’ website.

“I cannot guarantee that we are aware of every incident of hurtful behavior among students, but I can guarantee that students do alert us to such behaviors, and we do address them in a timely and effective manner,” he wrote.

He thanked the local police, state police and First Selectman Paul Formica.

— Kimberly Drelich