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The cause of an October high-rise apartment fire in the Brentwood area that injured eight people, including three firefighters, was ruled undetermined, fire officials announced Wednesday.

At least one unit in a 25-story building in West LA was on fire Oct. 18, 2013.

The fire’s cause was listed as “undetermined, most probably discarded smoking material,” according to a Los Angeles Fire Department blog post.

The fire broke out on the 11th floor of the 240-unit Barrington Plaza apartments on Wilshire Boulevard just before noon on Oct. 18, 2013.

Five residents were transported to hospitals for smoke exposure, according to the Fire Department’s Brian Humphrey. A child who was among the five victims was in critical condition, Humphrey said.

Three firefighters were hospitalized with minor burns and later released, officials said.

The 25-story building, one of three in the Barrington Plaza complex, did not have fire sprinklers, which were not required when the structure was built in 1961, according to the Fire Department.