The burned and broken streetcars and buses lining the esplanade here bore mute witness to the violence of politics in West Bengal, where the Congress-I Party of Prime Minister Indira Gandhi has taken to the streets of Calcutta to challenge this state's Communist-dominated government.

More than 20 persons have been killed and at least 150 hospitalized during the past two weeks in political demonstrations that tuned violent. Among the dead and injured were women and children caught on state-owned streetcars that were firebombed.

Streetcars now have metal screens around the front window instead of glass to protect the motormen from attack. One Congress-I member of Parliament, Ashok Sen, described of a demonstration by his party as nonviolent because only a few brickbats and firebombs were thrown.

West Bengal's Communist chief minister, Jyoti Basu, blamed the firebombing and violence on Garidhi's Congress-I (for Indira) supporters here, whom he called "hooligans" trying to topple his government so they can take over. He arranged for the lineup of the damaged buses and streetcars in the center of Calcutta to whip up opposition against the Gandhi suporters.

"We are dealing with gangsters, not a political party. How can we allow them to be in power?" asked Basu.

Gandhi repeatedly has denied charges that she is orchestrating demonstrations to topple Basu's government. Nonetheless, she has encouraged her party members in West Bengal to continue their antigovernment demonstrations, which included a general strike on April 3 that effectively closed public services in Calcutta. The strike ended with three Congress-I members shot by police, who found themselves surrounded in the mass protest.

"The big question here is, will she or won't she [toppled Basu's government], and if so, when?" said an observer of West Bengal politics.

One major brake to a full-scale Gandhi push to take over the state government is the weakness of her Congress-I supporters here. They are seen as unlikely to win any voting test against the ruling leftist front, especially its dominant component, the well-organized Communist Party of India (Marxist). This is India's communist faction most independent of Moscow.

Some analysts believe Gandhi is trying to weaken the front in advance of a series of state and muncipal elections during the next three months in hopes of achieving gains that could catapult Congress-I into a position of power in state assembly voting scheduled for March 1982.

Even if the party cannot gain power in the elections, the demonstrations are see as a means of keeping her party faithful in West Bengal on board by giving them an outlet for their opposition.

By staging demonstrations that end in violence, the Congress-I leaders are able to accuse the leftist front of failing to maintain law and order -- one of Gandhi's major campaign issues when she was voted backed into national power in December 1979.

Basu's front handed the Congress-I a powerful issue when it announced the end of the teaching of English in the state's primary schools. The move was first attacked by Congress-I joined in to demand the retention of English in the lower schools.

The current violence started March 30 when Congress-I held a demonstration protesting what oppostion leaders charged was a "deteriorating" law-and-order situation in West Bengal.

According to reports in Indian newspapers, the demonstration near the large mall in the center of Calcutta was peaceful until several Congress-I leaders courted arrested. At that point, eyewtnesses said, the outnumbered police were pelted with bricks. They responded with tear gas, and when they ran out of tear-gas shells fired bullets. Three persons were killed.

According to the Indian Express, the Congress-I demonstrators set fire to two streetcars -- a traditional Calcutta tactic in demonstrations -- and to two police vehicles in the area.

The demonstrations escalated April 3 when Congress-I called a general strike to protest the police action four days earlier. The strike practically paralyzed Calcutta. There were no private buses, rickshaws, taxis or trains running and state-operated bus and streetcar traffic was curtailed.

The streetcars and buses that did operate on the near-empty streets were subject to blistering attacks that left close to 20 persons dead and more than 150 injured. About 140 buses and streetcars were damaged, 400 persons were arrested and 64 bus and streetcar drivers were among the injured.

Some observers said the general strike was successful because people either feared violence or wanted a day off rather than because of strong support for Congress-I.

On April 6, the leftist front held a mass silent march in the center of Calcutta to mourn those who died as a result of Congress-I's general strike. The march tied up rush-hour traffic.

Many of those who died on April 3 were innocent victims. For example, a 12-year-old boy was burned to death when a firebomb missed a streetcar but exploded next to him. Three women, one pregnant, were killed when at least three firebombs were thrown at a crowded wooden double-decker bus they were riding in. Scores more were injured.

It appears that the Congress-I Party has borrowed the politics of confrontation developed by the Communists when they were an opposition party in the late 1960s and early 1970s.

The question, though, is whether it will succeed in undermining the leftist front to the point where Congress-I can return to power.