Police say two hoax devices caused the evacuation of Titusville High School Thursday morning that shut down area roadways and impacted thousands of drivers.

"The device was clearly designed to simulate an explosive device by whoever found it," said Deputy Chief Todd Hutchinson of the Titusville Police Department in a news conference. He would not describe the look of the device.

However, school system leaders described that the devices were made of PVC pipe, wrapped in duct tape.

Hutchinson said a custodian found the devices in a breezeway and field at the school around 8 a.m. right as students were arriving for the day.

Staff called the police, which contacted the Brevard County Sheriff's Office's bomb squad. They came on the scene and used a robot to inspect the device, explained police.

Students and faculty were evacuated to the football stadium and as the incident wore on many students were allowed to leave campus or be picked up by their parents. Titusville High School is closed on Thursday.

Area roadways, including busy U.S. 1 a right in front of the school, were shutdown to traffic. The campus was swept by bomb-sniffing dogs and a drone and the all clear was given.

Investigators say whoever did this had clear intentions to frighten people.

"Those responsible will be held accountable," said Hutchinson, who added that no faculty or students were hurt.

Authorities said 100 of the students had arrived at the school and 700 were on buses as the suspicious devices were found.

The Police Department is working with the FBI, which was on campus. Hutchinson said authorities are aggressively working to find out who is responsible and that this hoax was a big drain on resources.

Investigators say they are reviewing school security cameras. 

Officials say the school will re-open as normal on Friday.