WASHINGTON — One person was seriously injured in a fire in an apartment building in the District on Monday morning.

The D.C. fire department says the fire started at about 7:30 a.m. in a 10-story apartment building on Bladensburg Road, in Northeast. The department said the fire started in a seventh-floor apartment, and the occupant of that apartment has been taken to a hospital with serious but non-life-threatening injuries.

Another resident was being evaluated at the scene for possible exposure to smoke. A cat was found in the apartment where the fire started; Animal Control is examining it.

The building houses mainly elderly people, D.C. Fire said. People on the seventh through 10th floors of the building have been told to shelter in place. D.C. Fire said it determined it was safer for those people to stay put than to try to evacuate all of them.

The cause of the fire has been ruled accidental.

WTOP’s Victoria Rossi contributed to this story.