Milford School District's director of operations was seriously injured in a single-vehicle crash near Greenwood on Monday morning.
Heinz Retzlaff, 63, was airlifted to Christiana Hospital where he was listed in critical condition Monday evening, according to Delaware State Police.
Retzlaff was driving a 2011Honda Accord east on Shawnee Road, just east of Utica Road, when his car left the south side of the roadway before striking a tree about 11 a.m.
Police said Retzlaff was not wearing a seatbelt.
The crash remains under investigation.
Shawnee Road in the area of Utica Road was closed for nearly four hours while police cleared the area.
"We're very saddened and concerned," Sylvia Henderson, the school district's director of support services, said Tuesday. "We're keeping Mr. Retzlaff and his family in our thoughts and prayers."