UPDATE, 12:30 p.m.: A lockdown at Fordson High School has been lifted after three and a half hours.
District spokesman David Mustonen confirmed that students will continue with the school day "as normally as we can." Dual enrollment students were permitted to leave.
After school activities will also continue as planned, although an education rally planned for 2:30 p.m. this afternoon has been postponed, organizers report.
Mustonen said that the district is confident that the threat was not serious, but that they felt it was necessary to take the lockdown precautions.
"We have to take time to let police investigate," he said. "In this day and age, and with what happened in Ohio, you have to take everything seriously."
Mustonen also added that the student who attempted to leave was arrested by police for not following lockdown procedures that prohibit anyone from leaving or entering the school. The student allegedly told police that he had to leave to take his sister somewhere, and was handcuffed after "putting his hand on an officer," Mustonen said.
"He had nothing to do with the threat," he added.
Dearborn police Sgt. Douglas Topolski said that charges may be filed against the student who attempted to leave.
Topolski also added that there are no leads on suspects, but that police did not find any credible threats either.
UPDATE, 12 p.m.: Dearborn Police Chief Ronald Haddad confirmed that an anonymous phone call was made this morning by a person stating that they had a gun.
Haddad said that police believe it to be a prank, but would exercise due diligence in investigating the call.
Parents told Dearborn Patch that they had been sitting outside the school since the lockdown began around 9 a.m. Thursday morning, waiting for their kids to be released. Dozens of cars lined the side streets next to Fordson High as parents discussed the situation with each other outside of the school.
Several Dearborn police cars were at the scene.
"They need to get this situated," one mother said, who added that her kids have been texting her from inside the school all morning.
Students inside of the school reported to Dearborn Patch via text messages that the situation inside the school is calm.
Students also reported that one male student attempted to leave the school, but was quickly apprehended by police.
No arrests have been made in the threat, according to Dearborn police.
is on lockdown Thursday morning after a phone threat was made to the school.
Dearborn police sent out an alert about the lockdown at 10:50 a.m., but assured that all students are safe and that police are on the scene investigating the situation.
Stay with Dearborn Patch for more information on this situation.
Correction: This article originally stated that a student was arrested after trying to leave through a window. Dearborn Public Schools have confirmed that the student actually left through a door.