A first-grade teacher at a Silver Spring elementary school was charged with several counts of assault Tuesday, when authorities accused her of choking and, in some cases, punching half the 16 students in her class.

The incidents happened in December, in her class full of 6- and 7-year-old students, Montgomery County police said. None of the students was harmed seriously enough to require medical treatment or show visible injuries, law enforcement officials said.

It is uncommon for teachers to be charged criminally over actions in their classrooms, particularly physical encounters against multiple children.

Montgomery school officials said they learned of the allegations Jan. 4 and immediately removed the teacher, Susan Lee Burke, from Greencastle Elementary School and placed her on administrative leave. School officials looked into the accusations and referred the matter to child protective services workers.

Separately, on Jan. 7, a 7-year-old boy arrived at the Briggs Chaney police substation with a parent, said Capt. Paul Starks, a police spokesman. The boy said Burke had assaulted him numerous times, according to documents filed to support her arrest.

Detectives eventually interviewed all of the students in her class and found that eight said they had been assaulted, police said.

"All of the victims described being choked by the suspect," detectives wrote in the arrest records. "Some of the students, in addition to being choked, stated they were kicked, punched, scratched or had their arms squeezed tightly by Susan Burke."

It is unclear whether Burke has retained a lawyer for the assault charges. A phone message left at Burke's home was not returned. A man who picked up the phone listed to Burke's father declined to discuss the matter.

"I have no comments. Thank you," he said before hanging up.

Burke remained in the Montgomery jail late Tuesday. A court commissioner set her bond at $75,000. If she does not post it, she will probably go before a judge for a bond review Wednesday afternoon.

Burke was hired by the Montgomery school system in 2001. She taught at Meadow Hall Elementary School in Rockville for eight years before making a volunteer transfer in 2009 to Greencastle, schools spokesman Dana Tofig said.

Doris Videla, president of Greencastle's PTA, was stunned.