SOUTH BURLINGTON, Vt. – The FBI and South Burlington police arrested an 18-year-old South Burlington High School student in connection with a series of escalating death threats against school officials and students.

Josiah Leach was taken into custody on a federal criminal complaint that accuses him of knowingly transmitting a threat in interstate commerce, city police Chief Trevor Whipple said in a news conference. Leach will be jailed over the weekend pending a court hearing next week, the chief said.

There was no immediate word on the motive. A coalition of local and federal law enforcement, aided by cyber-security experts and internet providers, cracked the case, Whipple said.

“The electronic trail was a huge help to us,” he said.

Leach’s name appears on an emailed “hit list” of students and staff targeted in the threats.

Police announced the arrest shortly after 8:30 p.m. ET Friday with the following statement: “The FBI working with the South Burlington Police have made an arrest in the SBHS student and teacher threatening case. An individual is in police custody.

“A Press Briefing by the South Burlington Police, South Burlington Schools and the Office of the US Attorney will be held at the South Burlington Police Department at 9:00 PM this evening. We realize this is short notice but we wish to notify our community as soon as possible. A press release and criminal complaint will be available at the conference and transmitted after the conference to this email group.”

Earlier Friday, a video circulated on social media that showed an individual repeating the murder threat against South Burlington High School staff and students.

Another emailed threat was received by specific students and staff Friday morning, Superintendent David Young wrote in an email.

The same message read aloud on the video was circulated as an email Thursday and contained a “murder list” naming five staff members and 11 students. The email triggered the third lockdown in three days and an early dismissal. The district canceled Friday’s classes at all city schools.

This video repeats an email threat sent to staff and students at South Burlington High School. The names have been redacted.

After the video was discovered, Chief Whipple said police had notified the parents of the students on the list but allowed families to decide what precautions they wanted to take.

Local, state and federal law enforcement and cyber-security experts worked nearly ceaselessly since the threats began this week, Whipple said. He called what happened “an affront to our entire community” and labeled the threats “unacceptable, and will now be addressed by our judicial system.”