A man surreptitiously angled a video camera underneath the skirts of several women as they ascended an escalator from the subway platform at Grand Central Terminal during rush hour, police officials said.

Jamarl Chambers, 21, hid the camera upright in a shopping bag on Thursday and aimed it underneath the skirts of the women, whom he had followed up an escalator from the Lexington Avenue subway station before alert transit police officers discovered him. The officers noticed Mr. Chambers ride up and down the escalator twice behind the women, each time placing the bag between their legs, before police confronted him at about 8 a.m. and saw the video camera, according to court documents and police officers.

Mr. Chambers was arrested and charged with one count of unlawful surveillance in the second degree. He pleaded guilty in Manhattan Criminal Court just after midnight on Friday and was sentenced to 10 days of community service, officials said.

Mr. Chambers admitted to making seven videos of women without their knowledge, three of which he said he had recorded on the day he was arrested, according to court documents.

The transit police officers who caught Mr. Chambers were part of a task force that on April 9 arrested a man, Freddie Johnson, who has repeatedly groped women on the subway.

Unlike Johnson, who has been charged with 53 sexual offenses on the subway, Mr. Chambers has no prior record of arrests, officials said.

Transit police in Manhattan have made 66 arrests so far this year for crimes involving sexual abuse and public lewdness. In 2007, transit police officers arrested 264 suspects for such crimes.