NEWARK, N.J. -- An infant died Thursday after being stricken at a downtown office of the state child welfare agency, police said.

The month-old boy, who has been in foster care since birth, had just arrived about noon at an office of the state Division of Youth and Family Services from a doctor's visit. He had received immunizations for hepatitis B and polio at the doctor's, said DYFS spokesman Andy Williams.

"When the aide arrived to bring the baby upstairs, he noticed he was having trouble breathing and there was blood in his nose," Williams said.

The aide brought the child to the office nurse, who began resuscitation efforts while emergency medical workers were called. The first-aid crew took the baby to Saint Michael's Hospital, where he was pronounced dead at 12:46 p.m., Williams said.

"It appears the baby had a reaction to an immunization," Williams said.

An autopsy is to be done to determine the cause of death, police said.

The child, whose name was not released, was placed in foster care immediately after being born Sept. 16, Williams said.

The foster mother had taken the infant to the doctor's. After the visit, a DYFS driver took the boy to the DYFS office, where the infant was scheduled to have a supervised visit with his natural mother, Williams said.

Bereavement counseling is being offered, Williams said.