A second-grader at a school in Dayton, Ohio, was stabbed Friday by a man who entered the playground while she and other students were at recess.

Dayton police are continuing their search for the man, believed to be 18 to 20 years old, who stabbed the 7-year-old girl on the playground at World of Wonder PreK-8 school.

The student, whose name has not been released, suffered serious injuries and remains at Dayton Children’s Hospital, according to Dayton police.

The preliminary investigation suggests that a man walked onto the playground about 1:30 p.m. and stabbed the girl, then left the area.

“A man stabbed somebody,” a school secretary told 911 dispatchers. “They stabbed them on the playground.”

During the same call, another employee is heard telling the secretary how the victim was doing.

“She’s laying face down and the police are here,” the employee said.

The school was placed on lockdown. Students were dismissed just before 4 p.m.

Principal LaDawn Mims-Morrow, in a letter sent to families of World of Wonder students, said, “a trespasser entered our playground during recess today and assaulted one of our students. The incident is being actively investigated by Dayton police, who are pursuing a lead.

“The quick action of district security, administrators and our staff and students allowed us to clear the area and enter the building in an orderly manner following the incident. The building was then placed on lockdown as authorities conducted their search through the neighborhood.”

Mims-Morrow said counselors will be at the school on Monday if students need them. She also said there will be additional security at the school in the days ahead “whenever our students are outdoors.”

David Lawrence, Dayton Public Schools chief of school innovation, echoed Mims-Morrow’s comment that police “have a very clear and strong lead and are working on apprehending the suspect.”

He said, “We can’t predict some of these types of things. Most of our schools have security resource officers as part of their regular operations.”

Lawrence said he was at the school, located in a neighborhood that struggles with crime issues, 2 or 3 minutes after the attack and brought extra security personnel with him.

Lawrence said he would like to tell parents “We will have lots of additional adults here (on Monday). This is an anomaly, something that just doesn’t happen every day.”

District spokeswoman Jill Moberley said World of Wonder school usually has one DPS security guard in the building, but the individual wasn’t there Friday. Moberley said she wasn’t sure if that was because of illness or some other issue.

Two security guards responded from Thurgood Marshall High School, which is two blocks away.

“The two guards who responded from Thurgood were there in an instant,” Moberley said.

Late Friday afternoon, police released a description of the suspect.

If you have any information about the suspect or this crime, you are asked to call Dayton police at 333-COPS or Crime Stoppers at 222-STOP.