A Manassas woman was charged with murder yesterday in the deaths of her two young children, whose bodies were found in a closet of a relative's town house near Herndon, Fairfax County police said.

The mother, Nhoueng Khlaut, 29, who relatives said had complained in recent months of "hearing a voice," was arrested late yesterday afternoon and held without bond in the county jail pending arraignment this morning.

Police said they had been called several hours earlier by a family member at the town house in the 2100 block of Ferguson Place about the deaths of 4-year-old Thi Nguyen and his 11-month-old sister, Vuy Thi Mihn Nguyen.

Police said autopsies will be conducted in the deaths, which were also believed to have occurred yesterday.

"The bottom line is that the cause of death is not obvious," said Officer William L. Coulter, a police spokesman.

The children and their parents live in a town house in the 9700 block of Beech Place in Manassas and had been staying with relatives of the mother in the 84-unit Reflection Lake town house complex, neighbors and police said. Police were called to the town house about 1 p.m.

The father, Duong Nguyen, who works in a lumberyard in Manassas, found his children in the first-floor closet of the town house, police said. Because some family members have difficulty speaking English, interpreters were called to the scene to assist in questioning.

Police said they are investigating the deaths as homicides. The deaths shocked neighbors in the modest complex of town houses on the border of Herndon and Fairfax County.

"This is an unusual occurrence," said Sandra Mount, an office assistant at the complex. "You see people every day and you just don't know what's going to happen from one day to the next. This is normally a very quiet neighborhood."

Bany Kong, who lives with his wife and two children in the Herndon town house, said he, his wife and his wife's sister, the suspect, came here 10 years ago from Thailand. He said his sister-in-law and the children had come to stay with them last Tuesday while the father went looking for a new job.

He said that earlier yesterday morning, his 9-year-old daughter had awakened him upstairs saying she could not find her cousins.

Kong said he went downstairs to investigate, found his sister-in-law in the closet, confronted her about the children and got no response. His daughter said she saw her aunt sitting in the closet with her eyes closed and covers over the children. As Kong then tried to telephone the children's father, the father showed up at the front door and discovered that his children were dead in the closet.

"The father can't do anything. He cried, cried, cried," said Kong in a telephone interview at his home last night. "This is very difficult."

Yesterday afternoon, the town house was cordoned off with wide yellow tape and guarded by police. Neighbors huddled together and whispered among themselves about what they had heard. Most watched silently as a stretcher draped with a white sheet wheeled away the two small bodies in bags.

Mount said the Kongs are "very quiet and their children are nice."

Neighbors of the Nguyen family in Manassas described the couple and their children in similar terms but also said they had noticed the mother sometimes sitting on the town house stoop wrapped in a shawl, rocking back and forth.

"She was real quiet. She used to stay to herself," said Paul Diggs, 35, who lives across the street from the family in the Georgetown South neighborhood.

Cpl. H.E. Myers, a Manassas City Police officer who lives next door, said: "They kept to themselves. They'd just watch the kids play. She was always to herself, a very quiet person."

"I'd see her walking her baby out here, kissing it and playing with it," said Myers's wife, Peggy. "She seemed like she was very loving."

Nguyen's sister said the mother had complained about hearing a voice "calling her stupid" and would run in fear of the voice. Bany Kong said he had recommended to her husband that she seek a doctor's help and that she went to a "brain doctor about a year ago," who said she was all right.