SAN FRANCISCO -- Scores of drivers along San Francisco's busy Park Presidio Boulevard were pulled over and ticketed for falling to yield to pedestrians during Friday morning's commute in attempt to halt a deadly escalation of fatal accidents within the city this year.

The number of victims claimed by the roadway carnage this year has already equaled those of all of 2006.The death toll has reached 34 -- including 22 pedestrians, one bicyclist and 11 motorists or their passengers.

However, it was three deaths this week that triggered a call for action from pedestrian advocates and forced police to take action.

"The events of this past week have been unacceptable," said Manish Champsee, president of Walk San Francisco, a pedestrian advocacy group.

On Tuesday, Marina Vafiadis, 83, died after being struck by a Muni bus.

The bus that hit her was traveling northbound on Park Presidio Boulevard at around 10:08 p.m., officials reported. Vafiadis was pronounced dead at the scene.

San Francisco police are continuing to investigate two other fatal hit-and-run accidents today that occurred during the weekend.

Mark Ashley, a 27-year-old Canadian Navy lieutenant, was struck and killed by a Mercedes Benz while crossing the Embarcadero early Saturday, according to the San Francisco medical examiner.

The driver of the Mercedes with front-end and windshield damage struck Ashley at around 1:50 a.m. at the intersection of Howard Street, police said.

Witnesses said the driver of the Mercedes continued southbound on the Embarcadero and was not located.

On Sunday, Roger Tennyson, 77, of San Francisco, was fatally struck in the 100 block of Sanchez Street near his house at about 1:30 a.m., according to police. Tennyson died at the scene.

To counter the trend, police officers began their crack down using plainclothes decoys around 7:30 a.m. Friday at Park Presidio Boulevard and Crossover Drive.

Over the next several weeks, police will target 19th Avenue, Geary Boulevard, Alemany Boulevard, Lincoln Way and various locations in the South of Market and Financial District.