A janitor at Roosevelt Elementary School, located at 951 Dowling Blvd., found blood on school walls Friday morning, according to San Leandro police Lt. Jeff Tudor.
Police were called to the school and found a wallet near the bloody walls that belonged to a San Leandro man who told police he was playing basketball around 11 p.m. Thursday night when he felt something hit his head, Tudor said.
The man said he could not remember any other details and was not cooperating with investigators, according to Tudor.
He suffered a blow to the back of the head, which required a few stitches, the lieutenant said.
No one is in custody in connection to the apparent attack, Tudor said.
Tudor said the incident is not connected to the elementary school.