Police in Oklahoma arrested a 15-year-old boy last week following a week-long child pornography investigation that uncovered hundreds of graphic photos and videos of young children, the Canadian County Sheriff's Office said Thursday.

While searching the teen's bedroom in Mustang, officers found "over 300 videos and images of pre-pubescent child pornography depicting children as young as 4 years old being raped and sexually exploited," according to sheriff's deputies.

Authorities seized multiple electronic devices from the boy's home. As of Thursday, investigators had uncovered more than 1,000 pornographic videos and images of pre-pubescent children, according to KFOR.

"This case is absolutely one of the worst we've encountered involving a juvenile suspect and child pornography," said Canadian County Undersheriff Chris West. "It's hard to comprehend how anyone, and especially a kid this young, gets involved so deep into the hideous world of child pornography."

Deputies started investigating after the Oklahoma State Bureau of Investigation's Internet Crimes Against Children Unit requested their assistance. The pornography was originally flagged by the National Center for Missing and Exploited Children.

Deputies moved quickly to secure a search warrant for the 15-year-old boy's home in Mustang due to the "volume of graphic, pre-pubescent child pornography being distributed from the home." Once authorities determined the suspect was a minor, they brought a certified child-forensic interviewer into the fold to help with the case.

Deputies descended on the teen's home on July 19.

"As our investigators were walking to the front door, the suspect actually opened it (and) peeked out," West said. "Apparently, by the look on his face, he was a bit surprised, and (he) slammed the door shut."

No adults were in the home when deputies first arrived. They secured the 15-year-old until his guardian or guardians were back at the house. They agreed to have the forensic interviewer speak with the boy, who gave a full confession.

Authorities took the teen to the Canadian County Juvenile Detention Center and the case was turned over to the Canadian County District Attorney's Office for prosecution.