(CNN) Seattle Public Schools sent home fewer than 100 students who arrived for class on Wednesday without complete immunization records.

Washington state law requires that students are fully vaccinated, be in the process of completing immunizations or have a signed certificate of exemption in order to attend school, the district said. It had set a Wednesday deadline for students to provide their vaccination information.

Sami Hoag, Seattle Public Schools' health services manager, said the district does not yet have an exact number of how many students were sent home.

As of Wednesday afternoon, about 500 children in the district had not confirmed their vaccination records, Hoag said, but about 400 have been cleared to attend school because they have confirmed appointments to receive vaccinations.

"There were 520 kids on the list but less than 100 were physically sent home because their parents got the message," Hoag said. "The vast majority of 500 kids now have confirmed appointments to obtain their vaccinations in the next few weeks."

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