Residents have NSI Communitybeen ordered to evacuate a 16-story apartment building in Ohio due to concerns about the stability of a neighboring building that was severely damaged by a deadly natural gas explosion last month.

A directive issued Monday by Youngstown officials gives residents of the International Towers building 72 hours to leave the site. The order came after an engineering firm determined that the neighboring Realty Tower building remains structurally unsafe and is in “danger of imminent collapse.”

About 170 people live in the International Towers, and city officials planned to meet with them Tuesday to discuss relocation efforts and help determine their needs.

The May 28 explosion blew out much of the ground floor of Realty Tower, killing a bank employee and injuring several others. Part of the ground floor collapsed into its basement and sent the façade across the street. Bricks, glass and other debris littered the sidewalk outside the 13-story building, which had a Chase Bank branch at street level and apartments in upper floors.

A crew working in the building’s basement area intentionally cut a gas line, not knowing it was pressurized, according to a preliminary finding by the National Transportation Safety Board. Investigators are still working to determine why the pipe was pressurized.