WASHINGTON -- Taxi drivers caused traffic delays by driving slowly through downtown D.C. on Thursday morning to protest city officials' decision to switch from a zone to meter fare system.

Dozens of cabs drove in circles around the Wilson Building Thursday morning, traveling below the speed limit and honking their horns.

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Cabs were jammed bumper to bumper on Pennsylvania Avenue at one point, and traffic was backed up between 12th and 14th Streets due to the protest.

Mayor Adrian Fenty's office is located inside the Wilson Building.

"I love driving a cab. How dare this guy sit up there in that building and tell us, 'I'm going to stop this,'" said Mike Cruz, who has driven a cab for 30 years.

Police closed Pennsylvania Avenue for a brief time, but the closure may not be related to the taxi protest. A motorcade was spotted in the area.

The drivers also launched a 24-hour strike, leaving some travelers in a bind. Cab drivers said last month that they will strike at least one day a week, rotating days, until they get Fenty's attention.

Drivers said they will target the downtown area and places popular with tourists.

They also said they may strike on opening day at the Nationals' new stadium on March 30.

The mayor announced the switch to meters in October.

Under the new system, which takes effect April 6, travelers will pay a base fare of $3, and there will be a 25-cent charge for every sixth-mile traveled after the first sixth-mile. Every minute spent stopped in traffic or traveling under 10 mph will cost passengers 25 cents.

Fees under the old system were based on how many different zones of the city cabs traveled through.