A major traffic situation unfolded Wednesday evening on the upper, westbound deck of the Bay Bridge, caused by a man illegally walking eastbound from San Francisco in a traffic lane.

Wednesday was a day for mental health crises happening on Bay Area roads, apparently. Because hours after a man having a crisis of some sort engaged police in a lengthy standoff in Walnut Creek, backing up traffic in multiple directions at the Hwy 24/I-680 interchange, another man walked onto the Bay Bridge and began making his way to Treasure Island on foot.

As Bay Area News Group reports, via a reporter who happened to be in a vehicle near where the arrest took place and who took video of the incident, CHP was called to the bridge at 7:24 p.m. on the report of the pedestrian. The Chronicle says the guy was on "the catwalk" of the bridge — perhaps the beam along the north side of the bridge deck. But CHP tells Bay Area News Group that he was walking in Lane 5, or the righthand lane if you're driving westbound, which had to have led to some near-misses with cars.

A single CHP officer arrived on the scene and attempted to make an arrest without backup, and this led to, as CHP Officer Mark Andrews describes it, "good Samaritans" getting out of their vehicles to assist with the arrest. Andrews says that the man refused to comply with the officer's commands.

As Bay Area News Group reporter Aldo Toledo observed and captured on video, at least two of these good Samaritans can be seen punching the guy on the ground in the effort to subdue him. At least three men besides the uniformed officer can be seen assisting with the arrest, and an ambulance arrived likely to take the suspect away after the arrest, though his injuries are unclear.

The Chronicle reports that the CHP officer himself sustained injuries as well.

The two righthand lanes of the upper deck were initially closed during the incident, and at 8 p.m. the righthand Lane 5 remained closed.

A later video in the sequence is below, and Toledo surmised that the "guy in white appears to be an undo," as in undercover cop. And two of the men assisting with the arrest may have gotten out of the same car.

Photo: Jack Nagz