Arlington officials suspended the license of a home day-care facility yesterday where a 4-month-old girl stopped breathing Wednesday and later died, saying they are investigating whether the provider was taking in more children than allowed under county zoning laws. The infant died later at a hospital.

Hien Bui, 42, who runs the facility in a house in North Arlington, is licensed to care for a maximum of five children, officials said. But a social worker who came to the house after the baby's death observed a "gross violation" of that rule, said Valerie Cuffee, supervisor of the county's Child Protective Services.

Bui's attorney, Thomas Peter Mann, said his client has acknowledged caring for as many as 32 children at a time. But he said she is helped by five assistants and her husband and provides excellent care. He called the baby's death "a terrible tragedy" and said Bui did nothing to cause it.

Police said the girl, whose name they would not release, stopped breathing at Bui's home on North Ohio Street on Wednesday afternoon and died later at Arlington Hospital. An autopsy was performed yesterday, but the cause of her death will not be known until further tests, they said.

"It could be a couple of weeks until a final determination is made on the cause of death," said Cpl. Justin McNaull, a police spokesman. "At this point, we're still involved in the investigation."

Mann said Bui and her family are grieving over the baby's death. He said the parents of the child came to her house yesterday "and told her that they know what happened was not her fault."

He said there is no indication that the baby fell. She had gone down for her nap in a crib in a quiet part of the house, and Bui checked on her every 20 minutes, Mann said. When the baby did not wake up, Bui tried to administer cardiopulmonary resuscitation, he said.

Mann said parents have been sending flowers and food to Bui, who he said is known in the community as "Mama Hien," and telling her they want to bring their children back to her home.

He said she will do "everything and anything" to correct the violation involving the number of children at her facility.

"She acknowledged candidly to Child Protective Services that she had too many kids," Mann said. "Even though the care of those kids was of the highest quality, she understands she cannot have that number of kids without the proper license."

Cuffee said the decision to suspend Bui's license was based on "what the Child Protective Services worker directly observed -- gross violations of the regulations."

Bui is licensed to care for five children with one assistant, Cuffee said. She declined to say how many children were observed in the home, saying the investigation is ongoing.

According to Virginia Taylor, the county's supervisor of child care services, Bui's facility has been licensed since 1983. She said county rules for home day-care providers call for a ratio of one adult to three children under age 2, and one adult to six children older than 2. The maximum number of children allowed at any day-care home in Arlington is nine, Taylor said.

Cathy Harrison, 34, said she has been leaving her 2-year-old daughter in Bui's care since the girl was 3 months old. Harrison lives around the corner from Bui's brick rambler and manicured lawn.

"She's been wonderful," Harrison said. "She runs an excellent day-care program."

Will Strang, a neighbor of Bui's, said, "We're happy to have them next door."