Ten men were arrested during a three-day undercover operation aimed at adults who investigators say tried to solicit sexual contact with children under 17 on the internet.

The Fort Worth Police Department led the multi-agency sting, dubbed Operation Spring Cleaning, which ran from April 1 to April 3. Participating agencies included the Tarrant County Sheriff’s Office, Texas Department of Public Safety, Crowley Police Department, Carrollton Police Department, Homeland Security Investigations, U.S. Secret Service, and the FBI.

Nine additional suspects remain under investigation.

Those arrested were identified as Jose Montalvan, 41; Stephen Milliken, 30; Humberto Aldana Caballer, 23; James Klump, 61; Jordan Kammerer, 26; Joel Stroud, 33; Santiago Luque-Calix, 28; Jose Morales-Puentes, 25; Michael Schweitzer, 48; and William Johnson, 19.

Authorities used multiple online platforms to identify and track the suspects. More details about the cases were not released because of their ongoing nature and sensitivity.

Police used the announcement to urge parents to monitor their children’s online activity.

“This operation is a strong reminder that law enforcement is already working to find anyone using the internet to target children,” Fort Worth police said in a social media post, “and to encourage parents to always be involved in who your children might be communicating with online or through social media platforms. Through continued collaborations, we remain committed to protecting our most vulnerable and holding offenders accountable.”

Officer Daniel Segura said the department maintains a dedicated focus on such threats.

“We are continuously working in protecting our young children,” Segura said, per WFAA. “Those officers are assigned full-time to keep an eye on these suspects and these people who want to harm our children, and we’re going to go after them.”