Due to ongoing threats officials say have not been resolved, the River Forest Public Library will open late Tuesday and has hired security “due to continued threats,” library officials announced.

“The Library has been dealing with various threats and harassing messages targeting the Library Director and the River Forest Police. We believe these threats have come from a specific individual who was initially issued a ban from the Library for violating Library policy. The Library has been cooperating with the authorities investigating the threats and continues to work closely with the River Forest Police Department to assure the safety of Library patrons and staff,” library officials wrote in an announcement Monday telling of the later opening.

The library, located in west suburban River Forest, will open at 5 p.m. Tuesday.

The nature and timing of the threats were not immediately disclosed.

According to the notification about the threat, hiring of security and later opening, officials explained that recently, the actions of the individual believed to be at the center of the threats have “escalated” and include sending letters to The River Forest Tennis Club, several residents and a staff member.

“The content of the letters has also shifted. They now name several staff members and make indirect threats to the Library at large,” the notice reads.

Library officials have made the determination that it s not safe to remain open without adding more security. A private security firm has been hired — set to start Wednesday morning —  to be on site at the library during all of its operating hours “until the situation is resolved.”

“We feel that the added security will ensure the safety of our patrons and staff,” library officials stated in the notice.

The River Forest Police Department was set to be on site Monday and Tuesday from 5 p.m. to 9 p.m.

Since there is no security available Tuesday from 9 a.m. to 5 p.m., according to the notification, the library will be closed at that time. When the facility opens Tuesday at 5 p.m., it will close at its usual closing time of 9 p.m.

“If you receive any threatening or unusual letters at your residence, we ask that you contact the River Forest Police immediately and turn the letters in as evidence. This is an ongoing investigation,” officials stated in the notification. “We thank you for your continued support, patience and understanding.”