HOWARD, Ohio (AP) — An Ohio sheriff says authorities are searching for a missing woman, her two children and a female friend in a case that has prompted an overnight lockdown at a nearby college.

Knox County Sheriff David Barber told WBNS-TV the boyfriend of one woman reported her missing on Wednesday, and that the woman's co-worker said she didn't show up for work on Thursday.

The co-worker went to the woman's home and noticed that things were out of place. The sheriff says police searched the house and found it in "an unusual condition," but he did not elaborate.

The woman's pickup truck was found abandoned Thursday on property owned by nearby Kenyon College. The college ordered a lockdown until 7 a.m. Friday of all students on the residential campus.

Copyright 2010 The Associated Press.