Gunfire hit a window at Achievement First Amistad High School in New Haven on Thursday morning.
Police said a round hit a rear window of Achievement First Amistad High School at 580 Dixwell Ave. at 8:10 a.m.
Officials said the school is in hybrid mode, with some students in the building and no injuries were reported.
A school lockdown was put in place, but has since been lifted, police said.
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No students, faculty or staff were involved, according to school officials.
"We take very seriously any event in our school that could present a threat to the safety of any of our students. We will have additional police presence outside our campus over the next few days. Simultaneously, we will take all actions necessary to support our students’ mental, emotional, and physical safety," Amanda Pinto, spokesperson for Achievement First, said in a statement.
According to police, the ShotSpotter alert of gunfire originated on West Hazel Street between Dixwell Avenue and Sherman Parkway.
Anyone with information is asked to call the New Haven Police Department at 203-946-6304.