A New York City police detective shot and killed one man and injured another after he was slashed in an attack inside an apartment building lobby in Chinatown last night, police said.

The detective, Martin Carrano, was inside the lobby of a condominium building at 123 Baxter Street speaking with a desk clerk when the two men confronted them at around 10:30 p.m.

The men asked whether they could rent a room. When the desk clerk turned them away, they lunged toward the detective, slashing him in the back of the neck with blades that officials said may have been razors.

Officials said Detective Carrano left the lobby after he was attacked, but came back as the assailants turned on the clerk and began slashing her.

Detective Carrano fired about 10 times toward the attackers as the clerk lay on the floor, police officials said.

One of the men, who was not identified, was killed after being shot in the abdomen. The other man, whose identity was also being withheld as of last night, was also shot in the stomach and was stable after undergoing surgery at St. Vincent’s Hospital.

The desk clerk was recovering from cut wounds to the left side of her face and her right thigh. She was not identified.

Officials said that the detective, who is assigned to the 114th Precinct in Queens, had been meeting with the desk clerk about a domestic violence complaint she had filed yesterday. The clerk apparently called the detective earlier in the day to say she had been receiving harassing phone calls from a former boyfriend. A spokesman for the police department, Deputy Commissioner Paul Browne, said Detective Carrano had gone to visit her yesterday evening to discuss her case after finishing his shift.

Police officials said it did not appear that the two men who attacked last night knew her, however.

“The motive remains unknown,” Mr. Browne said.

Neither of the two men have previous criminal records, according to police.

Speaking after midnight at a press conference on Baxter Street, the police commissioner, Raymond Kelly, said Detective Carrano was expected to be released last night from Bellevue Hospital after receiving stitches.

Officials said Detective Carrano has served 20 years on the police force.

Mr. Kelly said most of the attack had been caught on surveillance cameras that were being reviewed by police.