A rabbi's 27-year-old son was badly burned during a pre-Passover ritual yesterday morning on 42nd Street in Borough Park, Brooklyn, when he poured paint thinner on a ceremonial fire, the police said.

Four other onlookers, including two young children, were also burned when the can of paint thinner exploded.

The accident had some local officials calling for greater safety measures and oversight of the annual ritual, which involves burning leavened bread and other food not permitted during the Passover holiday.

Though the Fire Department is tolerant of the fire rituals, by yesterday afternoon Ladder 148 in Borough Park had put out 125 blazes deemed unsafe, Capt. Michael Gala said.

Yesterday, as the first evening of Passover was beginning, it was unusually blustery, and in the city's heavily Jewish neighborhoods, sidewalks were ablaze with small fires that were difficult to control. In Borough Park, the air smelled of toast.

While many of the blazes were uncontained, a fire in front of a synagogue and yeshiva used by the Breslov sect of Hasidic Jews was burning in a five-gallon metal pail, a fire official said.

Because the wind kept putting out the fire, the son of the Breslov rabbi, identified by witnesses as Moshe Schick, was trying to revive it with paint thinner. But some embers were still burning, and just as he poured, a gust of wind came up and the stream of liquid vaporized in a flash, a fire official said.

Mr. Schick, with his father looking on, dropped to the ground and rolled, yelling "call Hatzolah," the private Jewish ambulance service, said one witness, Yaakov Baum, 20, a student at the yeshiva. "He was on fire rolling toward me," Mr. Baum said. Another witness, who would not give his name, said that at one point Mr. Schick rolled under a car and had to be pulled out.

"They do it every year with these liquids," Mr. Baum said. "If it's cold and windy, people say, 'Make the fire a little bigger.' " Newspapers, books and cardboard are used as fuel.

A 2-year-old, a 9-year-old, a 15-year-old and a 50-year-old, all male, were also burned in the explosion, a spokesman for Staten Island University Hospital said. All four were in stable condition at the hospital's burn unit.

The 50-year-old's hands were covered in second- and third-degree burns because he had tried to put out the fire, said the hospital spokesman, Brian Morris.

But Mr. Schick, who Mr. Baum said has three daughters, was the most seriously hurt, with burns covering 20 percent of his body, including his torso, arm and face. He was also at the burn unit, in serious but not life-threatening condition, Mr. Morris said.

Passover celebrates the flight of the Jews from Egypt some 3,000 years ago.

According to tradition, they left quickly and there was no time to let the bread rise, so during the eight days of Passover, Jews eat matzo, a cracker-like flat bread.

Preparation for the burning ritual begins the night before Passover, when families go through their houses, searching by candlelight for leavened bread and other forbidden food, often collectively referred to as chametz.

Sometimes, the bread is deliberately hidden throughout the house. The next day, before the evening's Seder meal, the chametz is burned and a prayer is said, it is believed, to release the family of ownership.

According to Rabbi Jack Meyer, who said he serves as a liaison to the Fire Department in Borough Park, people have occasionally been hurt during the burning of the chametz. "But never anything like this," he said. "Let's hope they learn a lesson."

Captain Gala said the Fire Department had set up a special command post yesterday in Borough Park, just as it had done for years in Williamsburg. "If it's a controlled fire for religious purposes, no threat to safety, we move on," he said. "We ask the officers to make good judgments."

State Assemblyman Dov Hikind, who represents the area, said he and City Councilman Simcha Felder would call on the community to find a better way to control the fires. Mr. Hikind said he found it ironic that yesterday morning he had given an interview about how the Police Department had stepped-up antiterrorism measures during Passover and two hours later he was talking to reporters about an entirely different kind of danger.

"We've been lucky for a long, long time in not having a serious situation, but we've reached now the point that we need to do something about it," Mr. Hikind said. "Yes, we're going to continue doing it, but we need some strong supervision."

In heavily Jewish areas, like those in Rockland County, some synagogues offer controlled burning at specific times.