(CNN) -- The Cook County, Illinois, jail remained on lockdown Friday morning as authorities searched for a weapon a "credible source" said had been smuggled into the building, a spokesman for the Cook County Sheriff's Department said.
Steve Patterson said the lockdown started at 7:15 p.m. Thursday in all 10 of the jail's divisions. Authorities escorted visitors from the premises and limited movement inside the walls.
All 736 detainees in the all-male maximum-security Division 10 were moved from their cells to temporary confinement in the basement or gymnasium as jailers searched every part of the facility, Patterson said.
Officers worked through the night, scouring about 1/3 of the cells in Division 10 by 5 a.m. Patterson said the search will continue, with replacements possibly brought in to replace fatigued officers who stayed up all night.
Patterson said he expected authorities would gradually lift the lockdown on nine of the jail's divisions as Friday progressed but the maximum-security area is expected remain on lockdown for an extended period of time, as officers continue "the tedious and meticulous process of searching every inch of Division 10."
He did not say what type of weapon authorities were searching for.