An infant was killed and a 2-year-old boy and two women were seriously injured last night when they were struck by a car as they tried to cross a busy street near a Prince George's County shopping center, authorities said. They were among at least six pedestrians who were struck yesterday in Prince George's and Montgomery counties, two of them fatally.

Shopping packages and purses lay scattered across New Hampshire Avenue just after the 7 p.m. accident on New Hampshire Avenue near Langley Park Shopping Center. The women, ages 24 and 30, and the toddler were struck soon after they stepped off the curb, officials said. They were not in a crosswalk.

The infant, whose sex was not immediately known by a police spokeswoman, died before reaching a hospital. The toddler was listed in fair condition last night at Children's Hospital. The women were in serious condition at Washington Hospital Center.

The driver stopped, and the preliminary police investigation indicated that pedestrian error caused the accident, said Officer Debbi Sabel, a county police spokeswoman. The names of the pedestrians were not immediately available.

About 8 p.m., an unidentified man was fatally struck as he tried to cross the 7700 block of Landover Road in Prince George's, authorities said.

About 2 p.m., a 25-year-old Germantown woman was was struck by a 1995 Pontiac Sunfire as she walked across Great Seneca Highway at Dairymaid Drive in Germantown, Montgomery County police said. The victim was flown to Maryland Shock Trauma Center, where she was in critical condition last night.

Neither the man nor the woman had been in a crosswalk.

Police investigate an accident on New Hampshire Avenue, near Langley Park Shopping Center.