(Bloomberg) — Optus, the Australian unit of Singapore Telecommunications Ltd., is facing multiple investigations and potential penalties after a technical failure that disrupted emergency calls and resulted in at least three deaths.

The outage occurred during a network upgrade Thursday and impacted the Triple Zero calls in South Australia, the Northern Territory and Western Australia. Follow-up checks revealed that three people died in homes that had tried unsuccessfully to make emergency calls, the company said late Friday when it disclosed the event.

Communications Minister Anika Wells told a news conference Saturday that Optus must explain why it failed to immediately notify emergency services and other relevant agencies. She added that regulators and state governments will conduct mu

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