A serious car crash on the Capital Beltway on Christmas Eve left six people injured, two of them critically, authorities said.

The crash occurred about 8 p.m. on the outer loop of the road in Montgomery County, fire officials said.

They said the incident occurred east of Connecticut Avenue. Two people’s injuries were adjudged critical, and three serious. One person suffered a minor injury, the fire department said.

No cause for the crash was immediately known.