SOUTH SAN FRANCISCO (CBS SF) — A water main broke Friday morning on Elm Street in South San Francisco, flooding several cars and forcing the evacuation of six houses, officials said.

The 60-inch pipeline broke around 9:45 a.m. on Elm Street between Park Way and Tamarack Lane, according to Charles Sheehan, a spokesman for the San Francisco Public Utilities Commission. The SFPUC owns and manages the pipe, which is part of the Hetch Hetchy water system that serves 2.5 million Bay area customers.

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Repair crews and investigators have been on site since around 10:30 a.m., and water was shut off shortly before 1 p.m.

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Red Cross, police and fire officials are evaluating the structural integrity of the evacuated homes to determine if residents can safely return, according to Sheehan.

The pipeline is one of several that deliver drinking water to northern San Mateo County and San Francisco, Sheehan said. Water service has not been interrupted by the break.

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Residents affected by the break should check in with the Red Cross at 520 Tamarack Lane in South San Francisco.