Meredith Powell was booked into the Pierce County Jail for investigation of two counts of third-degree child rape and one count of communication with a minor for immoral purposes.
"We received an anonymous tip on Tuesday and immediately provided that information to the police department," said Dan Voelpel, spokesperson for the Tacoma School District.
Police have not yet provided further details on the specific allegations against Powell.
Voelpel says Powell was placed on paid administrative leave Wednesday, then transferred to unpaid leave after her arrest on Thursday.
"This is extremely serious," Voelpel said. "We put all of our new employees through boundary invasion training which tries to draw those lines for teachers and other staff members that says 'these are lines we don't cross' and any time something like this is alleged, it's very disturbing."
Voelpel says Powell has been with the school district since September 2012.
Updates to follow as more details become available.