SAN LEANDRO -- A 7-year-old boy bit the hand of an man who grabbed him from behind and put a hand over the boy's mouth outside a school bathroom earlier this week, police said.

The boy ran back to his classroom and was not physically injured, police said.

Investigators said the incident occurred about 1:55 p.m. Tuesday at Jefferson Elementary School at 14300 Bancroft Avenue. But police were not notified by school officials until Friday morning, said Sgt. Ted Henderson of the San Leandro Police Department.

School staff sent out an automated phone message to parents Thursday evening alerting them to the incident, and police continue to investigate.

No one has been arrested.

"We're not sure at this point if it was an attempted abduction or if there was anything suspicious,'' Henderson said.

School principal Ruben Aurelio and district superintendent Cindi Cathey did not return calls or emails for comment Friday.

Police said the second-grade boy was grabbed outside of an interior bathroom in a school building, and the suspect was last seen in a school hallway.

Police said the suspect is about 18 years old and was wearing a white T-shirt, black jeans and black shoes.

Anyone with information about this case should call the San Leandro police department's criminal investigations division at 510-577-3230 or the anonymous tip line at 510-577-3278.

Anonymous tips can be texted to 837411 by including "SLPD." Anonymous tips can also be submitted to the department's website at http://www.sanleandro.org/depts/pd/at.asp\

Contact Erin Ivie at eivie@bayareanewsgroup.com. Follow her at Twitter.com/erin_ivie. Contact Kristin J. Bender at kbender@bayareanewsgroup.com. Followe her at Twitter.com/kjbender.