At least two city library branches were shuttered Thursday afternoon because of an ‘emergency,’ according to the library and witnesses.

Harold Washington Library, 400 S. State St. in the Loop and the Independence Branch, 4024 N. Elston Ave. on the Northwest Side have been closed.

According to a witness, shortly before 1 p.m. an Independence branch staffer made an announcement to everyone inside saying they were closing and everyone needed to leave. Additionally, staff there said: “All libraries are closing.” No one appeared to panic but it was not clear why they were evacuating.

We are closed “due to an emergency” said a recorded message at the Harold Washington branch’s phone system.

Chicago police had no details immediately.

Earlier this week, several libraries were closed including the Loop location, due to bomb threats.

Check back for details.

Lauren Fitzpatrick contributed to this report.