A 13-year-old seventh-grader at a nationally recognized Society Hill public school was arrested Wednesday morning after he was found to have a loaded handgun, authorities said.

The incident took place at Gen. George A. McCall Elementary School, a K-8 school on South Seventh Street near Delancey. Police said another student notified the principal that a male student had brought a gun into the school in the morning. The school was placed on lockdown from 9:28 a.m. to 10:04 a.m.

The teen was arrested without incident and a loaded semiautomatic handgun was recovered from the student's backpack, authorities said. No one was injured.

A call to the school's principal, Stephanie McKenna, was directed to school district spokesman Lee Whack.

"It is completely unacceptable any time a student brings a weapon to school," Whack said in an emailed statement. "The safety of our students and staff is always our top priority. … The gun was removed from the school without incident. The lockdown was lifted after it was determined that there was no further threat and all students and staff were safe. The School District is fully cooperating with the Philadelphia Police Department as they investigate this matter."

Because the student is a minor, Whack said he could not say what action the district might take.

The student remained in police custody Wednesday afternoon and was expected to face charges. It was not immediately known where he got the gun or why he had it.

Some parents in a McCall Facebook group expressed anxiety and concern that they were not immediately alerted that a student had a gun in school.

The school sent a letter, signed by the principal, home with students Wednesday, saying that a weapon was found on school property and that police were immediately contacted and the school placed on lockdown.

Paige Wolf, 38, who has a son in second grade at McCall, was at a school meeting with other parents in the library when the lockdown occurred. In a phone interview Wednesday afternoon, she said police responded immediately. After the lockdown was lifted, she went to her son's class. His teacher told her that "the kids dealt with it really well," Wolf said.

Because Wolf was already at the school, she said, she decided to take him home.

"When I left, everyone seemed calm," she said, adding that although she was upset, she applauded the school for its actions.

McCall Elementary was awarded a 2017 National Blue Ribbon for its high academic achievements from the U.S. Department of Education in September. The school, which educates 700 students, takes in a range of students, from Society Hill to Chinatown. Nearly 20 percent of its students are English-language learners, and it serves homeless shelters.

It was named the top-performing K-8 in Philadelphia by the School District last year.

Staff writer Patricia Madej contributed to this article.