A 22-year-old man has been charged with murdering his parents and three teenage sisters at their home in southeastern Iowa, a sheriff's office said Sunday.

Shawn Bentler is accused of gunning down five family members and faces five counts of first-degree murder, the Van Buren County Sheriff's Office said. He is being held on a $2.5 million bond at the Adams County jail in Quincy, Ill.

The victims were found early Saturday near Bonaparte, according to the sheriff's office. They were identified as Michael Bentler, 53; his wife, Sandra, 47; and their daughters Sheena, 17; Shelby, 15; and Shayne, 14. Autopsies were planned for Sunday.

Crack the case in FOXNews.com's Crime Center.

The sheriff's office said that it received a 911 call from Shayne Bentler at 3:38 a.m. Saturday and that she told the dispatcher her brother was "going to do something."

According to sheriff's documents regarding the 911 tape, a gunshot is heard in the background and someone screams, "Shawn, no!" The line then goes dead.

Authorities said they received a second 911 call at the same time from the cell phone of Sandra Bentler. That call went unanswered.

Bentler was arrested Saturday in Quincy, Ill., about 60 miles from the family's home, on an unrelated charge of possession of drug paraphernalia, according to the Adams County sheriff's office.

Jim Saunders, spokesman for the Iowa Department of Public Safety, said investigators have not offered a motive for the killings.

"It's going to take them a while," he said.

Earlier Sunday, at the St. Boniface Catholic Church in Farmington, where the Bentler family worshipped, some parishioners wiped away tears as they knelt to pray, while others sat transfixed, their hands on their faces or clasped in prayer.

"You saw this in the Amish country when those girls were shot, and now it's in our backyard," youth minister Mike Linnenbrink said, referring to the shooting deaths of five girls at Amish school in Pennsylvania this month. "It's not surprising at all that we turn to church at this time. This is a tight community, not just in Van Buren County, but in all of southeast Iowa."

The teens — a freshman, sophomore and senior — attended Harmony High School. School officials said they will have counselors available Monday to speak with grieving students.

Visit FOXNews.com's Crime Center for complete coverage.