The crash happened around 1:47 p.m. near US Highway 6 and White Thorne Lane in Porter County, Indiana, the sheriff's office said.
Two motorcycles and two other passenger vehicles were involved in the crash just north of Valparaiso, officials said.
Both motorcycle riders were killed at the scene of the crash, the sheriff's office said. Their identities, ages and genders were not yet known.
Traffic will be blocked in the area on US Highway 6 as the Porter County Crash Unit investigates, officials said.
This is a breaking news report. Check back for updates.