(Reuters) - Optus, Australia's No. 2 telecom carrier, said on Saturday it would cooperate with official investigations after three people died following a technical failure that disrupted emergency call services for 13 hours.

Amid a growing outcry surrounding the embattled company, two of the dead were identified as an eight-week-old boy and a 68-year-old woman, police in South Australia said. The third was a 74-year-old man in Western Australia, media have reported.

"I promise that we will fully cooperate with any and all investigations in relation to this," CEO Stephen Rue told a press conference, his second on the incident in two days, while repeating apologies.

The glitch occurred during a firewall upgrade for the network and lasted from 12:30 a.m. local time on Thursday until about 1:30 p.m., the company said.

Around 600 customers in the two states and in the Northern Territory were potentially affected. Optus has sought to make welfare checks with those people and has completed that process, Rue said. In cases where no contact was made, the checks have been handed off to the police, he added.

The Australian government on Friday promised to investigate what it called a "completely unacceptable" failure by the company, which is owned by Singapore Telecommunications.

Rue said on Friday that Optus had fixed the fault, was conducting a thorough investigation and would make the results public.

The incident comes less than a year after Optus was fined A$12 million ($7.9 million) by regulators for failing to provide emergency call services to thousands during a nationwide outage in 2023.

Optus also suffered a cyberattack in 2022 that affected the data of around 9.5 million Australians and a network-wide outage in 2023, which prompted the resignation of then-CEO Kelly Bayer Rosmarin. Rue took the reins in November 2024.