KIEV, Ukraine — A Ukrainian comedian who plays an accidental president on television delivered a walloping rebuke to the country’s political class in the presidential election on Sunday by emerging first in a crowded field of candidates, exit polls indicated.

The comedian, Volodymyr Zelensky, 41, captured more than 30 percent of the vote, according to two authoritative exit polls. It was a strong showing by a maverick with no political experience, though far below the 50 percent needed to win the first round outright.

If exit polls translate into real votes, Mr. Zelensky will face President Petro O. Poroshenko, who emerged second with around 18 percent, in a runoff in three weeks, on April 21. Yulia V. Tymoshenko, a former prime minister making her third bid for the presidency, was third with about 13 percent.

Official results are not due until Monday, and there will most likely be challenges, but the exit polls all reflected roughly the same results predicted by surveys before the vote. Turnout was estimated at about 63 percent in an electorate of 30 million people, slightly ahead of the 60 percent who voted in 2014.