FALMOUTH, Maine (AP) — An Oklahoma State University professor was killed and his wife critically injured in a head-on collision on a Maine highway Monday.

Busy holiday traffic came to a standstill for hours on Interstate 295 when a local resident entered the highway about 10 a.m. traveling south in the northbound lanes, causing a head-on collision, Maine state police said.

The collision happened near Falmouth, a few miles north of Portland.

The highway was closed for about three hours on Memorial Day.

Both drivers , state police said.

According to NBC affiliate, NECN, 72-year-old Nancy Ezhaya, of Yarmouth, and 61-year-old Allen Apblett, of Oklahoma, were pronounced dead at the scene.

Aplett’s wife was taken to a hospital in Portland in critical condition.

Dr. Allen Apblett. Image courtesy Oklahoma State University.

Dr. Allen Apblett was a chemistry professor at Oklahoma State University.

OSU sent the following statement:

The Cowboy family mourns the loss of Dr. Allen Apblett. He served the university’s chemistry department for over 25 years, cementing a legacy of scholarship and inspiring countless students. A distinguished fellow of the American Chemical Society, the National Academy of Inventors and the American Ceramic Society, Dr. Apblett was published over 100 times, holds multiple patents and awards and made lasting contributions to his field. The thoughts of the entire Cowboy family are with Dr. Apblett’s family at this time.