SOUTH SAN FRANCISCO (CBS SF) — CHP on Thursday afternoon said all lanes of southbound US-101 in South San Francisco have reopened following a solo collision and “critical incident investigation.”

CHP initially tweeted about the incident shortly after 1:30 p.m., saying that there was a critical incident on southbound US-101 at Grand Avenue in South San Francisco that had closed the #3 and #4 lanes of the freeway and the Grand Avenue off-ramp.

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All southbound lanes were briefly shut down, but a short time later the #1 and #2 lanes were reopened. There were online media reports that the incident was a shooting investigation.

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As of 1:40 p.m., CHP additionally confirmed that there was a traffic collision with injuries on southbound US-101 south of Grand Avenue that had closed the right lanes.

Just over an hour later, CHP confirmed that all southbound lanes had reopened. While CHP said they were investigating a solo vehicle collision, authorities referred any other inquiries about the incident to San Francisco police.