A 4-year-old girl was critically injured Sunday in a house fire in Southeast Washington, and authorities said they are conducting an arson investigation. Four other people were treated at hospitals after the fire in the 2600 block of 33rd street, officials said.

A man was arrested in connection with an incident that occurred after the fire, the D.C. police said.

Firefighters found the girl in the house after the blaze was reported about 3 a.m. in the house in the Naylor Gardens /Hillcrest area, officials said. Two women were admitted to hospitals in stable condition, one woman was treated and released and a small boy was also treated and released, authorities said.

A man who had also escaped the fire “made threats” against one of the women, said D.C. police spokeswoman Gwendolyn Crump. He also tried to assault her, Crump said Sunday night.

She said Jerome Calvary Lewis, 46, was arrested. He was charged with simple assault and making threats.

Crump said the investigation was continuing.

Police from the homicide arson unit were investigating, along with personnel from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives and the D.C. fire department, Crump said.

It was not clear what prompted the arson investigation.