CNN  — 

Ohio authorities are looking for a man who stabbed a 7-year-old girl at a school playground in Dayton.

The man walked onto the playground Friday, stabbed the second-grader and fled on foot, police said.

The unidentified victim is being treated for serious injuries at a local children’s hospital.

The attack occurred at World of Wonder PreK-8, and prompted the school to be placed on lockdown.

“We don’t know if at this point the child was targeted for some reason,” said Dayton Police Lt. Eric Henderson.

Video from CNN affiliate WKEF showed a line of police officers scouring the area, looking for evidence.

Principal LaDawn Mims-Morrow sent a letter to students’ families, saying counselors will be on campus Monday.

The school will also have additional security when students are outdoors, the principal said.

CNN’s Joe Sutton contributed to this report