City officials announced late Wednesday that a second claim of abuse has been lodged against a Harbor Middle School teacher's assistant accused of lewd conduct with a student.

Meanwhile, the assistant, LaShawn Hill, was arrested Wednesday night on larceny and forgery charges in connection with computers stolen from the school. Police say the arrest was unrelated to the investigation into the lewd-conduct charge.

Police Commissioner Ed Davis said Hill was issued a summons for lewd and lascivious conduct and will appear in Dorchester District Court on Thursday. Davis said a teacher from the King K-8 School notified police of a possible second incident that occurred last year.

At a City Hall press conference attended by Mayor Thomas Menino, Boston Public Schools chief Carol Johnson said that BPS has set a termination hearing for Hill. Between 2011 and 2004 Hill worked in the Lee Elementary, Lee Academy, King K-8, and Harbor Point schools.

Johnson said she has contacted school leaders at the four Dorchester schools for reports of similar incidents and urged parents, teachers, and students to come forward if other incidents occurred.

"When things like this come up, we need to be aggressive and assume that this may not have been an isolated incident," Johnson said.

City officials have sent intervention teams to the four schools and established a help line (617-635-3050) for concerned parents and an emergency meeting was held at the Harbor Point School Wednesday night.

Menino commended police and school officials for their quick response to the abuse, which came to light Monday afternoon when a teacher discovered Hill and a 14-year-old nonverbal student partially undressed in a break room and contacted the police.

"We are taking this matter very seriously," Menino said. "This one person will not change the confidence I have in Boston Public Schools."