SARA OLKON, GAIL EPSTEIN NIEVES AND MARTIN MERZER,

Torrents of protest flowed through Miami streets Thursday, a day after U.S. officials ruled that 6-year-old Elian Gonzalez must return to his father in Cuba. Hundreds of Cuban exiles staged hit-and-run sit-ins that blocked major intersections and disrupted traffic.

Demonstrators broke through barricades meant to contain them during a noontime rally at the Claude Pepper Federal Building on Southwest First Avenue, then surged through downtown streets. They chanted, ``!Libertad! !Libertad!''

Late into the night, protests still flared up and down Flagler Street and in other parts of Little Havana.

One rally persisted for hours at West Flagler and 57th Avenue. At one point, dozens of protesters joined hands, sat down and formed a circle that encompassed the intersection. Some climbed onto roofs and chanted ``Elian! Elian!'' from 20 feet in the air.

``We lost the street,'' Miami Police Lt. William Schwartz said.

Police arrested nearly 100 people countywide, including activist leader Ramon Saul Sanchez. Their hands were cuffed with white plastic ties. They were taken away in white prison buses. Most were charged with misdemeanors like obstruction of justice.

No physical damage was reported, and reports of direct confrontations and injuries were few.

But as night descended, a red car barreled into protesters on Flagler Street and Le Jeune Road, catapulting two of them. An ambulance carried both to a hospital. There was no word on their injuries. Police quickly pulled the car over and made an arrest.

``We did a blockade in the road and the car didn't want to wait,'' said Jorge Martinez, who was standing on the corner. ``He just floored it.''

In addition, Schwartz said an officer was hit by a car at Southwest Eighth Street and 27th Avenue. The officer's name was not immediately released, but he was in stable condition at Mercy Hospital.

POLICE ON ALERT

Police remained on alert everywhere, particularly around the new AmericanAirlines Arena, site of a Miami Heat-Houston Rockets basketball game and adjacent to an area that attracted demonstrators throughout the day.

``We will maintain a presence until we're sure there won't be any more protests,'' said Ed Munn, a Miami-Dade Police spokesman. ``If we have to stay here all night, we'll stay here all night.''

As the day unfolded, traffic was paralyzed in some areas. Drivers of school buses and public buses tried to reroute themselves around disruptions. Many drivers sat trapped in traffic for hours.

Gov. Jeb Bush ordered state workers to lift tolls on State Road 836 and other local roads Thursday evening to ease any rush-hour congestion created by the protests. Tolls were expected to be reinstated this morning.

But some activists vowed to escalate the action in days to come - until the courts or the Clinton administration reverses the decision by immigration authorities to return young Elian to Cuba by next Friday.

``This is going to continue and grow to a higher pitch until we get an answer from the White House,'' said Julio Cabarga, who heads Los Municipios de Cuba en el Exilio, an anti-Castro group. ``Being arrested is a very small price to pay.''

SOME DISAGREE

Many disagreed with that strategy, including some in the exile community.

Miami-Dade Mayor Alex Penelas said he shared the protesters' anger, but he begged them not to block traffic or create other disruptions that punish innocent bystanders.

"I cannot condone nor support any activity that infringes on the rights of others,'' Penelas said.

Hialeah Mayor Raul Martinez agreed.

"We have to not look out for the right of one group, but for the rights of the entire community,'' Martinez said. ``We're hurting ourselves. When this gets on national television, what sympathy is the rest of the country going to have?''

Asked about the propriety and strategic wisdom of traffic disruptions, Cabarga said:

``We are not going to apologize for doing what we are doing. I'm sorry that some people may be a little late for dinner, but if he [Elian] goes back to Cuba, he will not have any dinner.''

As the protests gained momentum, startled downtown motorists found themselves confronted by flag-carrying crowds marching through traffic on busy Flagler Street and Biscayne Boulevard.

STREETS CLOSED

Portions of those streets and others were temporarily closed, often by police seeking to contain large demonstrations that fractured into smaller, mobile protests. Traffic backed up in both directions on the MacArthur Causeway after police blocked exits to Biscayne Boulevard.

The Miami-Dade school system dismissed headquarters personnel at 3 p.m., 90 minutes early, after hearing reports that protests could spread to the downtown building.

A phalanx of Miami-Dade police officers, equipped with helmets, plastic shields and other riot gear, gathered on Biscayne near the Port of Miami-Dade and blocked protesters' progress into the port.

A stable-ful of mounted police joined the effort, which unfolded in the shadow of the Freedom Tower, a processing center for Cubans who entered the United States after Fidel Castro seized control of their country in 1959.

About two hours later, after dozens of people were arrested, that demonstration evaporated. The boulevard and the entrance to the port reopened. But police closed the area sporadically through the evening as other groups of demonstrators approached.

A large police presence also was evident at Miami International Airport. More than 150 Miami-Dade Police officers mustered in case the protests spread there.

As of Thursday night, one or two people who tried to stop their cars at the airport entrance were ``shooed away'' by police, said Lauren Stover, an airport spokeswoman.

Most people arrested in the protests and charged with misdemeanors did not spend the night behind bars, jail spokeswoman Janelle Hall said.

DOWNTOWN RALLY

The day's real action began shortly after noon as about 300 protesters gathered for the downtown rally. Demonstrators waved Cuban and U.S. flags, carried protest signs and chanted slogans.

Ramiro Menendez of Miami held up a bright yellow sign that said: ``Elian's mother died to save him from Castro; Clinton will reward Castro by sending Elian back. What a shame.''

Jorge Castro of Kendall watched with dismay. He said he was there to measure the size of the crowd, which was smaller than many expected.

``When everyone talks about the Cuban exile community supporting this kid, what are they talking about?'' said Castro, who left Cuba in 1961. ``They may control the Spanish radio stations that try to manipulate everyone with their propaganda, but they don't represent the entire Cuban community in Miami.''

In any event, small, apparently spontaneous demonstrations arose in many areas.

About a half-dozen workers from an on-line financial newspaper gathered at Coral Way and Southwest 32nd Avenue at 1 p.m., waving signs and yelling to passersby. Cars and trucks joined in, pulling up alongside and honking horns.

Sections of Southwest Eighth Street resembled a miniature Calle Ocho festival. Passengers in one of every three or four cars waved Cuban flags. A white van held up traffic in both directions as passengers waved flags.

HUNGER STRIKE

Earlier in the day, five men started a hunger strike under a canvas tarpaulin set up near the federal building. Dagoberto Avilez, 64, a former Cuban political prisoner, pledged to drink only water and refuse food until Elian is allowed to remain in the United States.

``I'm here to defend the U.S. Constitution, the law of this country, which President Bill Clinton has violated by his decision to deport Elian Gonzalez,'' Avilez said.

During the morning rush hour, two dump trucks and a pickup truck slowed all three lanes of eastbound traffic on S.R. 836. The Florida Highway Patrol issued $83 citations to drivers slowing traffic and warned them that they could be arrested.

Esteban Asensio, who drove the pickup truck, seemed undaunted.

``What they're doing is immoral, illegal and the kid needs to have a date in court,'' he said. ``At least I can do something.''

It was that magnitude of passion that worried authorities. Miami Police canceled all off days today, and Miami-Dade Police said they were prepared for more action.

``This is the first day and it's a work day,'' said Carlos Alvarez, director of Miami-Dade Police. ``They've got until the 14th, right?''

Herald staff writers Karen Branch, Anabelle de Gale, Allison Klein, Jasmine Kripalani, Eunice Ponce, Chuck Rabin, Joseph Tanfani, Sabrina Walters, Jay Weaver and David Wilson contributed to this report.