BROWARD COUNTY, Fla. – A former Broward County middle school teacher was arrested Thursday on numerous child pornography-related charges.

According to an arrest affidavit, authorities began investigating Ronald Sherman, 55, who worked at Apollo Middle School in Hollywood, in January after receiving information that he had been uploading child pornography images to his Tumblr account.

Broward County Public Schools officials said Sherman resigned "for personal reasons" on June 17.

Authorities said the images depicted Caucasian and Asian girls under the age of 10 who were nude and in sexually suggestive positions.

Tumblr employees alerted authorities about the images.

The South Florida Internet Crimes Against Children Task Force and Broward Sheriff’s Office SWAT team executed a search warrant at Sherman's home in Pompano Beach on Jan 31.

Authorities said Sherman admitted that the Tumblr account was his, but said that he stopped using it after the site notified him by email that his account had been deactivated because of a Terms of Use violation for "inappropriate activity."

According to the affidavit, Sherman said he would look at other Tumblr users' "walls," and would share content that would automatically go on his wall. He said he never uploaded images to the site and "wasn't really trying to do the kiddie porn thing," authorities said.

When shown printed-out images of the child pornography in question, Sherman told authorities that the images were "not sexual" and would be "considered art," authorities said.

Sherman was arrested Thursday after the ongoing investigation led to state search warrants of his Tumblr account.

Authorities said Sherman "reblogged" more than 4,000 images and videos before his Tumblr account was deactivated. A total of 800 of those images and videos depicted children, the affidavit said.

Authorities said most of the images and videos of children depicted nude or scantily-dressed girls between the ages of 3 and 12.

Neighbors who spoke to Local 10 News reporter Ian Margol Friday were shocked to hear that Sherman had been arrested.

"I was very upset because this is a good neighborhood," Danny Demato said. "It's nice and quiet. To hear something like that happened was a shock -- definitely a shock."

Sherman faces numerous charges, including possession of child pornography and promoting the sexual performance of a child. He is being held in lieu of a $240,000 bond.