The LaPorte County Sheriffs Department is investigating the incident which occurred on US 421 near Alida Road around 5:30 a.m.
Investigators believe a Ford Expedition, driven by a 44-year-old man was traveling north on US 421. That vehicle is thought to have collided with a Chevrolet truck driving southbound.
The truck was carrying four individuals from the Valparaiso area. Three of the passengers traveling in the truck were flown to an area hospital. The two others were taken via ambulance for treatment.
LaPorte County authorities remain uncertain as to how the vehicles crashed, but an investigation is ongoing. No names are being released at this time.
US 421 was closed for a period on Tuesday morning but has since reopened.