1934 West Coast waterfront Strike

July 5, 1934 was "Bloody Thursday":

After a quiet Fourth of July the employers' organization, the Industrial Association, tried to open the port even further on Thursday, July 5. As spectators watched from Rincon Hill, the police shot tear gas canisters into the crowd, then followed with a charge by mounted police. Picketers threw the canisters and rocks back at the police, who charged again, sending the picketers into retreat after a third assault. Each side then refortified and took stock.
The events took a violent turn that afternoon, as hostilities resumed outside of the ILA the kitchen. Eyewitness accounts differ on the exact events that transpired next. Some witnesses saw a group of strikers first surround a police car and attempt to tip it over, prompting the police to fire shotguns in the air, and then revolvers at the crowd. One of the policemen then fired a shotgun into the crowd, striking three men in intersection of Steuart and Mission streets. One of the men, Howard Sperry, a striking longshoreman, later died of his wounds. Another man, Charles Olsen, was also shot but later recovered from his wounds. A third man, Nick Bordoise--an out of work cook who had been volunteering at the ILA strike kitchen--was shot but managed to make his way around the corner onto Spear Street, where he was found several hours later. Like Sperry, he died at the hospital.
Strikers immediately cordoned off the area where the two picketers had been shot, laying flowers and wreaths around it. Police arrived to remove the flowers and drive off the picketers minutes later. Once the police left, the strikers returned, replaced the flowers and stood guard over the spot. Though Sperry and Bordoise had been shot several blocks apart, this spot became synonymous with the memory of the two slain men and "Bloody Thursday."
As strikers carried wounded picketers into the ILA union hall police fired on the hall and lobbed tear gas canisters at nearby hotels. At this point someone reportedly called the union hall to ask "Are you willing to arbitrate now?"
Under orders from California Governor Frank Merriam, the California National Guard moved in that evening to patrol the waterfront. Similarly, federal soldiers of the United States Army stationed at the Presidio were placed on alert. The picketers pulled back, unwilling to take on armed soldiers in an uneven fight, and trucks and trains began moving without interference. Bridges asked the San Francisco Labor Council to meet that Saturday, July 7, to authorize a general strike. The Alameda County Central Labor Council in Oakland considered the same action. Teamsters in both San Francisco and Oakland voted to strike, over the objections of their leaders, on Sunday, July 8.

The history of the whole strike is interesting.  1934 was a big year for strikes:

The 1934 West Coast Waterfront Strike (also known as the 1934 West Coast Longshoremen's Strike, as well as a number of variations on these names) lasted eighty-three days, triggered by sailors and a four-day general strike in San Francisco, and led to the unionization of all of the West Coast ports of the United States. The San Francisco General Strike, along with the 1934 Toledo Auto-Lite Strike led by the American Workers Party and the Minneapolis Teamsters Strike of 1934 led by the Communist League of America, were important catalysts for the rise of industrial unionism in the 1930s, much of which was organized through the Congress of Industrial Organizations.

It is notable that the National Labor Relations Act, or Wagner Act, was signed into law by FDR on the one-year anniversary of Bloody Thursday.