A Santa-suited gunman who killed six people on Christmas morning was the estranged husband of one of the victims and the father of two teenagers who died in the massacre.
Aziz Yazdanpanah, 56, showed up to his estranged wife's apartment on Christmas morning dressed like St. Nick and opened fire shortly after the family had unwrapped presents.
Yazdanpanah then killed himself.
The six victims were identified by ABC affiliate WFAA as: Nasrin Rahmaty, 55, who was Yazdanpanah's wife; Nona Yazdanpanah, 19, his daughter; Ali Yazdanpanah, 15, his son; Zohreh Rahmaty, 58, his sister-in-law; Hossein Zarei, 59, his brother-in-law; and Sahra Zarei, 22, his niece.
The medical examiner's office has still not released the names of the victims.
Zarei owned a popular Dallas, Texas, ranch and was well known in the Iranian-American community, according to WFAA. On Christmas Eve, the family hosted a party at the ranch. The gunman was not invited.
The scene the next day appeared like a typical Christmas day celebration before the carnage.
"The appearance we got leading up to this was it was just a normal Christmas gathering," Sgt. Roger Eberling of the Grapevine Police Department told ABCNews.com.
Eberling said it was unclear whether AzizYazdanpanah was invited to the apartment, but said it appeared he did not force his way inside.
Around 11:16 a.m., Eberling said a female victim sent a text message to a friend indicating the family had just exchanged gifts and that the gunman was there dressed as Santa Claus.
Minutes later, police received a 911 call, which initially sounded like silence, Eberling said.
After listening to the call again, Eberling said police could hear someone in a raspy voice saying "help me." He said the caller sounded out of breath and the call went dead after 15 to 20 seconds.
Police arrived within minutes where they found the bodies of all six victims and the gunman. Two handguns were found among the wrapping paper and Christmas tree.
Nasrin Rahmaty had been separated from her husband since March, according to ABC affiliate WFAA. Rahmaty and her two children moved into the Grapevine, Texas, apartment where they were murdered, while Yazdanpanah reportedly remained in the family's Colleyville, Texas, home, which had been foreclosed on last year, WFAA reported.
Yazdanpanah had been having financial troubles after his real estate business slowed down and had reportedly filed for bankruptcy.
"I swear i never had a good feeling about him when i met him," Katherine-Anne Coronado, who said she was longtime friends with Nona Yazdanpanah, wrote about her friend's father on a Facebook memorial page.
Another family friend, Sedi Toumani, agreed.
"During the years, we sensed things, but not to the point he would take his own children's lives," Toumani told WFAA.
Grapevine, a town that sits on 16 square miles near Dallas, was still in a state of shock, Eberling said. The last homicide in the town was in 2010.
"We never really have encountered a situation with this many victims that were shot and killed," he said. "We're still trying to uncover the background here. This is the worst homicide we've ever had."