A thorough sweep of Ponchatoula High School using bomb-detector dogs turned up no suspicious items and the school was declared secure Thursday morning, the Tangipahoa Parish Sheriff’s Office said.

An anonymous threat earlier in the day prompted the closure of the school for the day.

Superintendent Mark Kolwe said late Thursday morning that the high school’s campus had been cleared by law enforcement to return to normal activities.

“If there are any other activities, they will go on as scheduled,” Kolwe said.

Sheriff’s Office detectives are investigating the source of the call, which was received by the Ponchatoula Police Department at 5:28 a.m.

The Sheriff’s Office said it appears the call was placed from the Baylor Scott & White Medical Center in Carrollton, Texas.

Kolwe said he received the first notification about the bomb threat at about 5:50 a.m. Thursday, when Principal Danny Strickland called him. Some school buses already were en route, but text messages, social media alerts and a notice on the district’s website alerted bus drivers and parents of the situation and the buses took the students back home, Kolwe said.

In addition to telling students to stay home, police were notified. Approximately 40 law enforcement officers from several agencies, assisted by school staff, took part in the hourslong sweep, the Sheriff’s Office said.

Authorities urge anyone with information regarding this incident to contact Crime Stoppers at (800) 554-5245 immediately.

The school will reopen for classes on Friday, the school system said, adding that all elementary and junior high schools in Ponchatoula were open Thursday.