NORTHBROOK, Ill.— A semi-truck has slammed into an Illinois State Police squad car in Chicago's northern suburbs, killing a state trooper.

The Illinois State Police says Trooper James Sauter was pronounced dead at the scene of the crash, which took place late Thursday on Interstate 294 on the edge of Northbrook.

The cause of the accident is under investigation.

The 28-year-old trooper joined the Illinois State Police in June 2008.

In a statement released Friday, State Police Director Hiram Grau expressed his "deep sadness" over the trooper's death and offered condolences to his family.

He said Sauter left a "legacy of courage, honor and duty."