A bride-to-be was shot dead in front of her family Sunday by a former boyfriend who walked uninvited into her New Jersey home as the family was about to leave for the wedding, the authorities said.

The former boyfriend, dressed in wedding clothes, walked in about 4 P.M. as the woman was posing for a final round of photographs, pulled a gun out of a briefcase and shot her, prosecutors said.

As a white Rolls-Royce and two stretch limousines for the wedding party idled outside the home that the woman, Gladys Ricart, 39, shared with her 20-year-old son and her mother, the gunfire sent a houseful of guests scrambling for cover, hiding in closets and running down to the basement, said the Bergen County Prosecutor, William Schmidt.

The former boyfriend, Augustin Garcia, was arrested at the scene -- a quiet street in the small Bergen County town of Ridgefield -- and was expected to be charged with murder, prosecutors said.

A neighbor across the street who heard her dog bark came out to see what the commotion was about and saw bridesmaids in light green and champagne dresses running onto the lawn. "They ran over to my steps and sat down, and they were crying," said the woman, who would not disclose her name. The flower girl for the wedding was whisked into a neighbor's house to get her away from the violence, the woman said.

Ms. Ricart's fiancé, James L. Preston, 36, of Brooklyn, was to meet her for the ceremony at the Church on the Hill in Flushing, Queens, and was not present when the shooting occurred, the authorities said. A message left on Preston's answering machine last night was not returned.

Ms. Ricart and Garcia, 47, of North Bergen, N.J., had dated for about six years and had broken up several months ago, Schmidt said.

Schmidt refused to say whether Garcia had been stalking Ms. Ricart or whether she had an order of protection against him. Rafael Heres, a relative of Ms. Ricart's who was at the house, told Channel 5 News that Garcia appeared deeply troubled.

"We already knew the guy's background, and we figured that the phenomena would occur," he said. "He was a little negative. He couldn't accept rejection."

Ms. Ricart had met Preston about four months ago, Schmidt said.

Sunday afternoon, Schmidt said, Garcia apparently drove his black sport utility vehicle to Ms. Ricart's home on Elizabeth Street, a sycamore-shaded block of small tidy houses in a town of 10,000 people five miles west of New York City.

Garcia parked and walked into 825 Elizabeth, a two-family, brick-faced home where Ms. Ricart lived with her son, Davis Ricart, and her mother, Anna Rosario, Schmidt said.

Some of the guests recognized Garcia when he entered, Schmidt said. He would not say whether they asked Garcia to leave. When Garcia found Ms. Ricart modeling her wedding dress for the photographer, he shot her "several times," Schmidt said.

Afterward, investigators found a .38-caliber, five-shot handgun, which they described as the murder weapon, in the house.

Schmidt said Preston worked for a Brooklyn business called Double Click, but was unsure of the nature of the business. Authorities had not determined last night how Ms. Ricart and Garcia were employed.

Dozens of grieving guests were taken from the house to a nearby firehouse, where they were interviewed as witnesses -- and consoled -- by the authorities.

As Ms. Ricart's body was carried out of the house around 8 P.M., the white Rolls-Royce still waited outside.