A teenage girl and her boyfriend are accused in the homicide of the girl's grandparents, according to Gwinnett County Police.

Authorities found the bodies of Randall and Wendy Bjorge, both 63, inside their home on Furlong Run early Sunday. Officers made the discovery after a welfare check.

Investigators believe the couple's granddaughter, Cassandra Bjorge, 17, and her 19-year-old boyfriend, Johnny Ryder, are responsible. Police took the pair into custody after a short SWAT standoff at an apartment complex in Suwanee.

Detective David Smith said the two had self-inflicted cuts when found and are now being treated at a hospital.

Along with the duo's suspected involvement in the killings, police said Ryder beat two of his relatives with a baseball bat late Saturday at his mother's house on Rambling Woods Drive. Investigators said the assault sparked the search for the teens because a vehicle belonging to the Bjorge couple was found at the location.

Authorities told FOX 5 the pair's family from out-of-state called 911 after not hearing from them. They made another welfare check at the couple's home earlier in the week but were unable to make contact.

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