SAN JOSE, Calif. (AP) — Police say four Santa Clara County jail inmates are recovering after they overdosed on drugs.

KNTV reports (http://bit.ly/2uMne4n ) Santa Clara County Sheriff's Office Sgt. Rich Glennon says the inmates were taken to the hospital Wednesday afternoon following the overdose.

The jail was placed on lockdown while authorities investigated the incident. The lockdown was lifted late Wednesday night.

Three of the inmates had returned to the jail late Wednesday night and all four are expected to recover.

Jail officials say it is unclear what type of drugs the inmates took.

Problems in the jail over the last several years led to the creation of a commission charged with improving operations. The commission made 101 recommendations to the board of supervisors last year.

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Information from: KNTV-TV.