MILLBRAE (CBS SF) — Two people were found dead inside a submerged vehicle in a flooded underpass in Millbrae Thursday morning, authorities said.

A spokesman for the San Mateo County Sheriff’s Office said firefighters responded at about 5:45 a.m. to reports of flooding at Hemlock Ave. and E. Hillcrest Blvd. in Millbrae, where E. Hillcrest passes under Caltrain tracks.

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“Upon arrival, they noticed a person standing on the roof of a vehicle. The fire department entered the water to rescue the person in the vehicle. While doing that they realized that there was a second vehicle in the water,” said Sheriff’s Detective Javier Acosta. “So after they rescued the first person, they tried to gain access to the vehicle in the water. However, the conditions changed rapidly and it became too dangerous for the responders. The water was rising very rapidly and they had to retreat.”

Caltrain underpass where two people were found dead inside a submerged car on E. Hillcrest Blvd. between Hemlock Ave. and Aviador Ave. in Millbrae, December 23, 2021. (CBS)

Acosta said it took several hours for crews to drain water in the area, and once firefighters were able to access the second vehicle they found two people deceased inside.

“At this time we don’t know exactly what happened,” said Acosta. “However, there was heavy rain this morning.”

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Raw Video: San Mateo County Sheriff’s spokesman on discovery of two bodies in submerged car

The flooded location was one of several low-lying areas in San Mateo County flooded by an overnight rainstorm. The National Weather Service had issued a flood advisory for the area and warned some low-water crossings may be impassable.

“We are responding to multiple flooding calls across the coastal area in San Mateo County,” Cal Fire officials said earlier Thursday morning.

E. Hillcrest Blvd. between Hemlock and Aviador avenues was closed off for hours during the investigation. Just after 2 p.m., the sheriff’s office said Hillcrest had been reopened in both directions.

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