The man, who firefighters found on the steps in the house in the 3500 block of Sylvan Lane, was treated at the scene and was taken to the University of Maryland Shock Trauma Center in stable but critical condition, a news release from the fire department said.
A second family member was taken to a local hospital with non-life-threatening injuries, and a third was uninjured. Firefighters also retrieved two cats from the house.
Neighbors called 911 after seeing smoke coming from the back of the house around 11:30 a.m.
Because of the heavy snow, an enhanced team of about 70 firefighters from Howard and Baltimore counties were called to the scene, where they fought the blaze for about an hour.
They had the fire under control around 1 p.m., but crews remained to make sure it didn't flare up again.
The cause is under investigation by the Howard County police and fire departments. Damage estimates for the house were not immediately available, but the release indicated the home is expected to be declared uninhabitable later today.