Salina, NY – A 6-year-old girl died and her 14-year-old brother is in critical condition at Upstate University Hospital after an incident at their home earlier this morning.

No official cause of her death and his injuries has been determined, but carbon monoxide poisoning is a “strong possibility,” sheriff’s Detective Jon Seeber said.

The children’s father found the two unresponsive earlier this morning and called 911, Seeber said. Deputies arrived at 106 Carlton Drive around 7 a.m., Seeber said.

The house is taped off while authorities continue to investigate. Carlton Drive was closed between Bailey Road and Pitcher Lane until around 9:10 a.m.

“At this point, we are treating this as a crime scene,” Seeber said, but stressed that it’s too early to say whether the incident was accidental or intentional.