A 27-year-old secretary returning from work with her 3-year-old daughter in her arms was attacked and fatally stabbed last night as she walked to her Adams-Morgan apartment house, police said.

The woman, Clarine Collier-Wilson, was assaulted about 6:40 p.m. in the 1600 block of Lanier Place NW. She was carrying her daughter, Pareece, in her arms while her other daughter, Kamilla, 10, walked alongside, a relative said.

The slain woman's sister, Janis Collier, said last night that the children told her the assailant had tried to rob their mother. Police said they were investigating whether robbery is a motive in the attack, but one homicide official said investigators had not reached a conclusion.

Based on what the children told her, Janis Collier said her sister was returning to her apartment after picking up the 3-year-old from a Mount Pleasant day-care center when they were confronted on Lanier Place by a man who asked for money. The children said their mother responded that she had none.

She said the 10-year-old saw her mother's attacker raise his hand as if to strike her. The girl ran shouting for help.

Collier-Wilson was stabbed in the chest, just below the heart, her sister said. Rescue workers performed cardiopulmonary resuscitation, then took her to Washington Hospital Center, where she died at 7:13 p.m.

The incident occurred on a sidewalk next to the apartment house where Collier-Wilson lived, near Lanier Place and Harvard Street NW. She was about half a block from the driveway of her building when she was confronted.

One neighbor interviewed last night said the attack occurred near a strip of sidewalk that had been dubbed "muggers' row" after attacks there several months ago.

Collier-Wilson was one of eight children of a clergyman who moved to the Washington area from Florida almost 30 years ago. "She was a very lively, bubbly type of personality," the sister said. "She was very crazy about her two daughters."

Janis Collier, 38, said her sister worked for a company involved in defense contract negotiations.

She said Collier-Wilson had warned her only last week to be careful at night. "She told me I had a curfew," the sister said. "She said that all these muggers, they give you a grace hour to get home."

Sitting on the couch in her sister's living room, Janis Collier said last night that Pareece probably would go to live with her father, who had shared custody.

For the older daughter, last night's incident compounded an earlier tragedy. Janis Collier said Kamilla's father was found dead about a year ago in California under what she said were unexplained circumstances.

"She lost her father, she's lost her mother, when her stepfather comes to take her sister . . . her whole world has crumbled," she said.

Kamilla was told last night that her mother had died in the attack. The child sat silently in Janis Collier's lap, her head buried in her aunt's shoulder.

Late last night, the 3-year-old, Pareece, had not yet been told because her aunt said she thought the girl was too young to understand. Instead, she played noisily around the family's apartment with a cousin.