The reported abduction of an infant in Baltimore yesterday prompted Maryland's first activation of an Amber Alert, in which information about the missing child was broadcast immediately on radio and television and flashed on electronic highway signs.

Maryland State Police Lt. Bud Frank said the alert was activated about 1 p.m., almost six hours after the reported disappearance of 2-month-old A'Shia Jenkins. The alert continued throughout the day.

The girl's father, Kenneth Jenkins of Baltimore, told Baltimore police that he was riding in an unlicensed taxicab in the northwest part of the city with his twin infant daughters when the driver stopped and robbed him at gunpoint. Jenkins said he then got out of the cab and put A'Shia's sister in a stroller. As he about to remove A'Shia from the cab, Jenkins said, the driver sped away with the girl still inside.

Frank said descriptions of the vehicle (a white, four-door, older model Honda Accord) and the driver (a black male in his early twenties) were posted immediately on highway signs across the Washington-Baltimore region and broadcast on radio and television.

The Amber Alert system is named for Amber Hagerman, a 9-year-old Texas girl kidnapped in 1996 and later found dead. There are about 50 Amber Alert programs nationwide, including 15 statewide systems, according to the National Center for Missing and Exploited Children.

In the Washington area, the Amber Alert system has been run by the Metropolitan Washington Council of Governments for more than a year. It includes the District and several jurisdictions in Northern Virginia and Maryland.

Maryland launched a statewide program in August. In Virginia, state officials have said they will ask the legislature this year to implement a statewide program.

Detective Donny Moses, a Baltimore police spokesman, said Jenkins reported A'Shia missing shortly before 8 a.m. He said Jenkins told authorities that he was picked up by the unlicensed, unmarked cab in northwest Baltimore, near Coppin State College.

Police said A'Shia, who is black, was wearing a purple snowsuit and hat, a pink T-shirt and yellow socks. The cabdriver was described as having black hair and wearing a black-and-white-striped shirt, black pants and black shoes. Baltimore police ask anyone with information about the case to call 410-396-2100.