The man believed to have killed six relatives and then himself on Christmas Day was dressed as Santa Claus, police said Monday.

The shooter "showed up shortly before the incident took place" in the Santa outfit and was a member of the family opening gifts in the apartment, said Grapevine police spokesman Sgt. Robert Eberling.

Eberling said the identity of the man and the victims will be released after autopsies are conducted later Monday.

The dead — four women and three men — were found late Sunday morning in an apartment living room in the Dallas suburb of Grapevine by police answering a voiceless 911 call, authorities said.

Two pistols were recovered from the home, said Eberling, who called it a "gruesome crime scene" and the worst outburst of gun violence in the town's history.