Two other van passengers and the officer involved also sustained injuries.
Sheriff's officials say Officer Mark Sickafoose was responding to an incident-- going east on Dupont with his lights and sirens on-- when his car t-boned the white van in the Diebold Road intersection.
The crash closed Dupont Road for several hours this morning-- and witnesses describe the scene as horrific.
"It was a lot of chaos out there... It was definitely a bad accident," says witness Wendy Souder.
Souder says she ran outside just after the crash happened.
She says an Allen County Sheriff's car had t-boned the driver's side of a white van in the Dupont Road-Diebold Road intersection.
"There was a county police car, and it's hood was damaged. I mean, what I could see. And then, I see later, you could see the white car and the side was smashed in," Souder says.
Sheriff's officials say Sickafoose was going east, with sirens on and lights flashing-- on his way to an incident on nearby Tonkel Road.
The van was turning left from Diebold Road-- when Sickafoose struck the driver's side.
The male van driver was initially listed in critical condition-- and later died.
Law enforcement has not yet released his identity.
However, the van was owned by "Unity Transportation"-- they say the driver was an employee of theirs-- and confirmed his death this afternoon.
Two female passengers, an adult, listed in serious condition, and a juvenile, had minor injuries.
Sickafoose had minor injuries from the crash.
"With it involving an officer and the officer being on-duty, and of course he was going to a scene, of course that is going to be further investigated," says Allen County Sheriff's Department Corporal Jeremy Tinkel.
Tinkel says Sickafoose has worked for Allen County since 2004, and has a clean record with the department.
He says they do not know the traffic-light situation at the intersection, nor how fast the vehicles were going.