TOWN OF HEMPSTEAD, N.Y. (CBSNewYork) – A Long Island elementary school teacher is accused of child sex abuse.

Nassau County police say 51-year-old John Joseph Finnegan Jr. engaged in sexual contact with a 10-year-old girl and inappropriate behavior with at least two other female students.

Finnegan, a teacher at Jackson Annex Elementary School in Hempstead, was arrested Wednesday and charged with sexual abuse and endangering the welfare of a child. He has pleaded not guilty.

A Long Island elementary school teacher is accused of child sex abuse. (Credit: Nassau County Police Department)

Finnegan was out of the classroom Friday, in handcuffs, reported CBS2’s Carolyn Gusoff. West Hemsptead school officials call the charges against him “heinous acts,” allegedly committed while teaching an after school art program at Jackson Annex Elementary.

Police said he subjected the 10-year-old girl to sexual contact on Jan. 3.

“Our hearts go out to the children,” said Acting Hempstead School Superintendent Regina Armstrong. “To provide the counseling, to assure them that coming forward was the right thing to do.”

Court documents detail the allegations. Finngen allegedly asked the girl to bend over to pick up items and then inappropriately touched her. When he allegedly tried a second time, she tried to get away and he pulled her back, according to the documents. Two other children allegedly witnessed the acts.

The teacher’s attorney disputed the minors’ claims against Finnegan.

“Ten-year-old kids allegedly witnessing in a classroom filled with kids and staff members… these allegations are absolutely preposterous. My client is absolutely innocent,” Dana Grossblatt said.

Grossblatt said that Finnegan, beloved in the district for 23 years, could not have possibly committed these crimes out in the open.

Fellow teachers call Finnegan a highly regarded former union rep.

“I find that very disturbing, you know, my kids go here. Three of my kids go here,” Hempstead parent Diana Hernandez told CBS2’s Jenna DeAngelis.

“Tons of questions that race through your mind as a parent,” said another parent.

The investigation revealed two prior incidents of Finnegan allegedly behaving inappropriately toward young girls at similar after school programs, police said.

Teachers in Hempstead and throughout New York state undergo background checks, which have been required since 2002. Private schools are exempt, but there’s a bill to close the loophole.

“There have been sad incidents throughout the country where someone who was convicted of offenses involving children were hired by schools that didn’t run background checks,” said St. Sen. Todd Kaminsky (D-Rockville Centre)

The acting superintendent of schools sent a letter to parents on Jan. 9, saying “several students reported to their building principal that their teacher had inappropriate contact with them. Immediately, an investigation commenced, and the teacher was assigned to home.”

“This was done to eliminate any risk that the alleged behavior would continue,” the letter continued. “The District’s policy is Students’ first.”

The letter also said the “District will protect the students who have come forward.” The district says it is providing counseling for the children involved.

Finnegan has been on a forced leave of absence since early January.

Police encourage anyone who thinks their child may have been victimized to call the Special Victims Squad at 516-573-4022 or Crime Stoppers at 1-800-244-TIPS. All callers will remain anonymous.