A 17-year-old student was arrested in connection to a fire that erupted in a building at Monrovia High School early Monday morning, officials confirmed.
The fire was reported just before 12:30 a.m. at the high school's administration building located in the 800 block of West Colorado Boulevard, according to the Monrovia Police Department.
A neighbor heard sounds of glass breaking and saw a person throw an object into a window and running away.
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Monrovia police said the teen male, who was a senior at the school, was arrested on suspicion of arson after admitting to starting the fire. Officials also said there was evidence on the teen that lead police to believe he started the fire.
The fire caused extensive damage to counseling offices and extended into classrooms on the upper floors.
Officials assured students and parents that there were no ongoing threats to students' safety and school resumed as scheduled Monday.
Students were relocated out of the main building into other classrooms on campus, officials said.
Fire crews remained on scene into the afternoon to assess the damage.
No injuries were reported.
There was no immediate word on a motive for the attack.