BERKELEY (BCN) — Dry rot caused the deadly collapse of an apartment balcony in Berkeley last week, city officials announced today.

The fourth floor balcony collapsed during a party in unit 405 at 2020 Kittredge St. at 12:41 a.m. on June 16, killing six people, including five Irish nationals, and injuring seven others.

The balcony directly below that one was removed later in the week after city inspectors found it was also at risk of collapse. Two others were red-tagged as unsafe.

City officials said this morning that the deck joists of the fourth floor balcony were found to be severely dry rotted, likely causing the collapse. The Berkeley City Council will take up new building and inspection regulations in the coming weeks designed to prevent similar catastrophes in the future.

The five Irish nationals killed were all 21 years old and visiting the country on J-1 visas, which allows visitors to participate in work and study-based exchange programs.

They were identified as Olivia Burke, Eoghan Culligan, Niccolai Schuster, Lorcan Miller and Eimear Walsh.

The sixth victim was Rohnert Park resident Ashley Donohoe, 22, who had worked for the last eight months as a forensic assistant intern with the Sonoma County coroner’s office.