A 45-year-old man faces murder and arson charges for allegedly setting the fast-moving fire in a lower Manhattan apartment building that killed a woman and left six families homeless.

Police said Wei Chu Wu set the Thursday night fire at 41 Spring St. after arguing with his girlfriend, the mother of his 13-year-old son.

The argument in their second-floor apartment started over Wu's suspicions that she was cheating on him, police said.

After the fire started, Wu allegedly fought with responding firefighters and police, trying to keep them out of the five-story building. An officer from the nearby Fifth Precinct in Chinatown suffered a broken hand in the scuffle, said NYPD spokesman Paul Browne.

Wu, of Manhattan, was charged with arson, second-degree felony murder, attempted assault on a police officer and resisting arrest, Browne said.

Wu's girlfriend and child were not harmed, but investigators found a woman's badly burned body on the fourth-floor fire escape. A spokeswoman for the city medical examiner said the victim died of smoke inhalation and thermal injuries. She wasn't immediately identified.

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The New York office of the American Red Cross said six families were displaced by the fire and that the agency had provided housing for two of them.

A spokeswoman for the Manhattan district attorney's office expected that Wu would be arraigned late last night or Saturday.