(CNN) -- Ferry service between San Francisco and points north will be suspended Tuesday morning in anticipation of an expected protest, a regional transportation agency said.
The Golden Gate Bridge, Highway and Transportation District announced Monday that there will be no ferry service across San Francisco Bay between the northern California city and Larkspur and Sausalito until about 2 p.m. Tuesday.
The agency said it has been engaged in ongoing contract talks with unions representing 375 of its employees, with the next negotiating meeting set for May 7.
It said there were reports there will be anything from informational picketing on the Golden Gate Bridge to efforts to shut down traffic on the bridge as well as all ferry services, though those possibilities have not been confirmed by the unions themselves.
"So that our customers are not inconvenienced tomorrow morning May 1 when they arrive at the ferry terminals with a strike action, and no service as a result, we are suspending service and informing our customers," the transportation district said, explaining its move.
The announcement was made at 3 p.m. (6 p.m. ET), two hours after the same agency issued a release stating it was "planning to operate all of our services (bridge, bus and ferry) on May 1."
There was no immediate response Monday from union officials as to what exactly is planned. An item on the Local 21, Professional and Technical Engineers' website urges union members to "take off all or part of the workday to participate in May 1 actions" including a Golden Gate Bridge "rally" from 7 to 10 a.m.
It is unclear what effect any actions might have on traffic on Tuesday on the iconic Golden Gate Bridge, which stretches between the city of San Francisco and Marin County.
The Golden Gate Bridge, Highway and Transportation District is in charge of the bridge, which 38 million vehicles crossed last year, as well as transit buses and ferry services that it estimates serve more than 9 million customers annually, according to its website.
A group of 21 Bay Area unions -- among them bridge and ferry workers, municipal employees, janitors, nurses, longshoremen and grocery store employees -- is planning several events on Tuesday to illustrate their "fight together to rebalance the distribution of wealth."
These include "supporting striking ferryboat workers at Bay Area ferry terminals" between 7 and 10:30 a.m. There will also be a janitors "walk-out" at the Westfield Shopping Mall, a march and street festival and an afternoon "bus tour of the San Francisco 1%," according to a press release Monday from the San Francisco Labor Council, one of the organizations that is part of the effort.