A man killed his mother and injured his sister late Monday in a stabbing at their home, the Orange County Sheriff's Office said.

Florida man kills mother, injures sister in stabbing, deputies say Adam Farney, 27, fatally stabbed Lori Farney, 52, and stabbed Autumn Farney, 23, shortly before 11 p.m. at the home, Orange County Lt. Ashley Strange said.

Investigators said Autumn Farney was in a bedroom when she heard an altercation, so she walked out to the back patio, where she discovered her mother on the ground.

Deputies said she saw her brother standing over their mother with a sharp object. They said he started to stab his sister but she managed to injure him, escape from the home and call for help.

Denton Smith said Autumn Farney was bloodied and had cuts all over her body when she ran to his home.

"She came running, crying, screaming, beating on the door," Smith said. "My wife woke me up."

After calling 911, she and Smith returned to Autumn Farney's home to retrieve her baby, who was sleeping in a bedroom.

Smith said Lori Farney was on the ground and Adam Farney was sitting quietly in the dark.

Autumn Farney was taken to a hospital with non-life-threatening injuries, Strange said.

Deputies said Adam Farney, who has a history of mental illness but no prior criminal record, was also taken to a hospital and will be booked into the Orange County Jail on first-degree murder and attempted first-degree murder charges.

"This is just a tragedy for a family to go through something like this," Sheriff's Office spokeswoman Jane Watrel said. "Any time of the year is bad, but we know during the holiday time, it's especially stressful. Our hearts go out to the family. This is just terrible."

Neighbors said they weren't aware of any previous problems at the home. They said Lori Farney was friendly and well-liked.

"It’s unbelievable, because they were decent, quiet people," Peggy Fuentes said.

The stabbings remain under investigation. Deputies said Adam Farney's motive is unknown.