SAN FRANCISCO (CBS SF) — A garbage truck caught fire Friday morning on northbound U.S. Highway 101, blocking the freeway and causing a traffic jam until crews extinguished the blaze.

The fire, reported about 11:30 a.m. near the Cesar Chavez off-ramp, fully engulfed the truck and prompted the California Highway patrol to issue a Sig Alert for heavy traffic.

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Garbage truck on fire near in San Francisco on hey202.

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The left two lanes reopened about 12:15 p.m., but responding officers expected lanes 3 and 4 to remain closed to traffic for about an hour for cleanup and inspection, the California Highway Patrol said.

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No injuries were reported. The cause of the fire remains under investigation.