Investigators on Sunday were interviewing several people, but no suspects had been named by late afternoon. Investigators were checking out tips that had come in to the sheriff's office, including leads and tips that came from outside Calaveras County, officials said.
"It's just terrible," area resident Paul Gschweng told Sacramento television station KCRA. "What can I say about it, it's just a tragedy."
The station reported that a neighbor told police that a man was running from the girl's home after the incident.
The suspect was seen wearing a black shirt and blue pants. Authorities considered him armed and dangerous.
Investigators were asking area residents to call authorities if they had any information, or knew of anyone who may have unexplained injuries, or may have left the area unexpectedly after the girl was killed.
Valley Springs is a community of about 2,500 people in an unincorporated area of Calaveras County, known as "Gold Country," in the foothills of the Sierra Nevada mountains, about 60 miles southeast of Sacramento.
The county became world-famous in 1865 with Mark Twain's short story, "The Celebrated Jumping Frog of Calaveras County," according to the Calaveras County Chamber of Commerce website.