Iowa ? Three high school girls and their parents were found dead Saturday morning at their home in eastern Iowa, and the couple’s son was arrested in Illinois and considered a suspect, officials said.

The victims were found shot about 4 a.m. near Bonaparte, according to the Van Buren County sheriff’s office. It was not immediately clear what prompted the slayings.

Shawn Bentler, 22, was arrested Saturday in Quincy, Ill., on an unrelated charge of possession of drug paraphernalia, the Van Buren County sheriff’s office said. The Iowa Department of Public Safety said he is a suspect in the slayings.

Quincy is about 57 miles southeast of the family’s home.

Parents Michael Bentler, 53, and Sandra Bentler, 47, were found dead with their daughters Sheena Bentler, 17, Shelby Bentler, 15, and Shayne Bentler, 14, Van Buren County authorities said.

The Harmony school district confirmed three of its female high school students and their parents were killed.