WINDHAM — Windham police on Tuesday night arrested a teenager they say was behind the email threats that closed area schools for most of three days, reaching a milestone in a case they say could have gone very differently.

Lt. Jim Boudreau of the Windham Police Department said at a Wednesday morning news conference at the town’s high school that investigators executed a search warrant at the suspect’s Windham home Tuesday evening.

“Some of the evidence collected indicates there could have been a danger to teachers and students,” Boudreau said, adding the email threats sent by the teen “made reference to the use of a weapon.”

The lieutenant said police believe the email threats were sent Sunday night, the two-year anniversary of the shooting at Sandy Hook Elementary School in Connecticut, where a gunman fatally shot 20 children and six staff members before killing himself.

In Windham, police say they apprehended the culprit before he was able to carry out his threats. A 16-year-old male was charged on eight counts of Class C terrorizing in the case — one count for each of the eight schools in Regional School Unit 14 evacuated Monday morning and kept closed Tuesday and Wednesday while police investigated.

RSU 14 Superintendent Sandy Prince said schools will reopen Thursday.

Police told reporters Monday that students at all Windham and Raymond schools were sent home just after 9 a.m., after two district administrators received distinct and threatening emails from different sources.

Boudreau said Wednesday police believe both emails were sent by the same individual, who is now in custody.

“The suspect obviously has some knowledge of the computer system, because the emails were disguised — he was trying to hide the source of the emails,” Boudreau told reporters. “We don’t believe there was anybody else involved in this. We are continuing to investigate whether he talked to anybody else about it, but we don’t believe anyone else was involved.”

The lieutenant, who was joined on the high school auditorium stage for the news conference by 25 other people, including fellow police, firefighters and school officials, said the 16-year-old suspect is not a student at RSU 14 schools but would not provide more details about him.

Prince said the suspect may previously have attended school in the district. He told reporters Windham police and Cumberland County Sheriff’s Office deputies will be stationed at all RSU 14 schools during the remainder of the week but stressed “that’s just for the sake of comfort.”

“The threat is now gone and behind us,” he said.

Prince said the schools will make counselors available for students who need them.

“I want parents to know the well-being of your children is the highest priority of this organization,” he said. “We will do whatever it takes to ensure a smooth transition [back to classes on Thursday] for your children.”