Ten people at an Oklahoma assisted living facility were hospitalized after they were given insulin injections instead of the flu shot, according to police.

The incident took place at the Jacquelyn House in Bartlesville, Oklahoma, about 40 miles north of Tulsa, after multiple people were found unresponsive, said Bartlesville Police Chief Tracy Roles.

Eight residents and two staff members were all hospitalized following the incident, but have since been released or will be soon.

Roles said that a licensed pharmacist was contracted by the facility to administer the vaccine. The pharmacist is cooperating with police and state officials, but investigators believe it was an accident.