SAN DIEGO -- An after-school program supervisor at an Arroyo Vista charter school is being investigated for allegations that he molested several children at the Chula Vista campus, it was reported Thursday.

A letter was sent to parents Tuesday stating that the YMCA child-care site supervisor was being looked at for possible "inappropriate behavior," according to The San Diego Union-Tribune.

"As soon as the YMCA was notified of the allegations, the employee involved was immediately removed and will not return to the Arroyo Vista site," said the letter, signed by principal Pat Roth.

Chula Vista police Sgt. John McAvenia said the unnamed supervisor has talked with detectives voluntarily and denied the allegations.

"He's already given his side," McAvenia said. "He's gotten himself a lawyer."

Investigators may ask the supervisor to take a polygraph test, McAvenia said.

Thu YMCA offers 176 child-care and other after-school programs countywide and estimates that it serves about 14,000 children daily.

It is not clear how the allegations came to light, but they arose during spring break, authorities told the Union-Tribune.

"It happened in an after-school setting with about a dozen kids in it," McAvenia said.

Police have interviewed two Arroyo Vista children and plan to interview a third Thursday, he said.

The YMCA learned of the allegations April 14, Pattie Griffin, vice president of marketing and communications for the YMCA of San Diego County, told the Union-Tribune.

"The YMCA is fully cooperating with authorities and in accordance with that, it would really be inappropriate for us to say anything more about it," Griffin said.

All YMCA employees are fingerprinted and their references are thoroughly checked, Griffin said. They also must sign a code of conduct.