CLEVELAND — Cleveland city officials said an investigation is underway into the "cyber incident" that closed City Hall on Monday, and they announced it will be closed again on Tuesday along with Erieview.

The cyber incident occurred Sunday, and its nature and scope have not been confirmed. Officials couldn't confirm many details during a press conference Monday afternoon due to the investigation, but they said they're working on keeping the "threat" contained. It's not known how long the investigation will last.

“Our utility departments, our airport departments are operational. That being said, I want to ensure the public, the city staff, that we are successfully going to manage and ensure that we are able to get back to a point of operation," said Kim Roy Wilson, commissioner of the Information Technology and Services Division.

Officials said the city shut down affected systems and focused on safely securing and restoring services. The systems were to remain offline until officials understood the situation better.

"City and emergency services including those in the Department of Public Safety (911, Police, Fire, and EMS), the Department of Port Control (Cleveland Hopkins and Burke Lakefront Airports), Department of Public Utilities (Water, Water Pollution Control, and Cleveland Public Power) are not affected," the city said in its release.

With systems offline, all daytime 311 calls will be handled by after-hours operators.

All public safety divisions, including EMS and the fire department, are operational. 

Reporter Nora McKeown contributed to this story.