Under the protection of police and the National Guard, crews under Chief Engineer C.H. Purcell resumed work on the San Francisco-Oakland bay bridge today.

With the entire area of construction patrolled, the workmen, withdrawn when yesterday's rioting spread to endanger their lives, again picked up their tools. The back-to-work order followed a tour of inspection of the battle zone by Chief Engineer Purcell.

The work resumed today included:

Excavation for viaduct on Rincon Hill's east side; demolition of buildings at Pier A on the west side of Beale st., pouring of concrete for Pier 1, on Spear st. at its intersection with the Embarcadero.

Despite the heavy guard, bridge workers remained in the bounds of "no man's land" by presence of the guard, however, it was pointed out.

The workmen, Mr. Purcell announce, had requested an additional patrol extending from the Embarcadero to take in the area bounded by Harrison, Second, Brannan sts and the Embarcadero.

Mr. Purcell said the request had been forwarded to Col. R.E. Mittelstaedt, National Guard chief.