Crime Two Teens Killed by Mother's Boyfriend After Argument Over Smoking in Their Home Della Jette, 15, and Sterling Jette Jr., 16, both succumbed to gunshot wounds to the chest at Waterbury Hospital in Connecticut By Eric Todisco Published on December 5, 2019 10:08 AM Share Tweet Pin Email Two Connecticut teenagers were murdered by their mother’s boyfriend, who then killed himself, following an argument over his smoking in the house, multiple outlets reported. According to local news outlet WTNH, Watertown Police Department said they received a 911 call around 9:45 p.m. on Tuesday night. The female caller, who identified herself as mother Danielle Jette, said that her boyfriend had shot her son and daughter. The teenagers, Della Jette, 15, and Sterling Jette Jr., 16, suffered gunshot wounds to the chest but were still alive when police arrived at 9:47 p.m. Della was found on the back deck at their Watertown, CT home, while Sterling was between the kitchen and living room floor, WTNH reported. According to CNN, the teenagers were transported to Waterbury Hospital and both were pronounced dead not long after their arrival. The mother’s boyfriend, 42-year-old Paul W. Ferguson, was found by police in the master bedroom with a self-inflicted gunshot wound. He was pronounced dead at the scene, WTNH, CNN, and NBC Connecticut reported. WTNH Mom, 19, and 1-Year-Old Son Are Missing as Family Receives ‘Strange Texts’ from her Phone According to CNN, the argument began between Della and Ferguson due to his smoking in the home. Ferguson then retrieved a handgun from his bedroom and shot Sterling in the leg after he tried to intervene. “The mother went downstairs to call 911 when she heard a second gunshot, presumably when he shot the daughter on the deck,” Gavallas Watertown Police Chief John Gavallas told CNN. “He came back in the house and shot the son in the chest.” Watertown Police Department did not respond to PEOPLE’s request for comment. Detective and police spokesman Mark Conway told CNN that Ferguson was a convicted felon and not authorized to possess a firearm. He was convicted of first-degree unlawful restraint after an arrest on a sexual assault charge in 2007, Conway said. According to NBC Connecticut, Danielle is cooperating with police in the investigation. RELATED VIDEO: Family of ‘Hero’ Boy, 13, Who Survived Attack in Mexico That Killed Mom Speaks Out “The boyfriend moves in the house two weeks ago for the holiday season. He’s gone and both her children are gone,” Gavallas told NBC Connecticut. “This mother is completely distraught as you can imagine.” Both teenagers attended Kaynor Technical High School in Waterbury, police told the outlets. Want to keep up with the latest crime coverage? Sign up for PEOPLE’s free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases. Jeffrey Wihbey, superintendent of Connecticut Technical Schools, released a statement Wednesday morning about the deaths of Della and Sterling, according to WTNH and CNN. “Our hearts go out to the students’ family and friends during this difficult time,” said Wihbey. “There is nothing worse that can happen to a school community. Our number one priority right now is doing all we can to support our students, staff and families through this crisis. Prior to the start of the school day, Kaynor Tech assembled the school’s crisis team. The team will provide grief counseling to students and anyone in the school community who may need it over the coming days.” The recent tragedy was not the first to strike the Jette family. Police also told the outlets that Danielle’s former husband, Sterling Jette Sr., killed himself in a self-inflicted gunshot wound to the head three years prior.