FBI Special Agents Daniel Alfin and Laura Schwartzenberger were killed Tuesday morning while executing a warrant at an apartment in Sunrise, Florida. The agents who were killed were key members of the division that tracks down pedophilic sex offenders.

Three other officers also injured when a man in the residence opened fire, fatally wounding them, at the Water Terrace apartment complex. According to the FBI, two of them were transferred to the local hospitals after they suffered multiple gunshot wounds.

FBI Agent Alfin, aged 36, helped topple one of the largest child pornography networks in the world in 2015. He was one of the officers who help top bring down Playpen in 2017. Playpen had tens of thousands of followers. Steven W. Chase of Naples, the operator of the site, was sentenced to 30 years in prison.

Both the officers worked for the Crimes Against Children team, which works to track down child prostitution, child pornography, pedophilic sex rackets, and also people who travel around the world to pursue sexual activities with minors.

Schwartzenberger, a 43-year-old mother of two, also had become an integral part of the sex crime unit. She worked seven years for the Crimes against Children.

The name of the shooter who died during the confrontation has not been released by the FBI.