May 19, 1984

The fire that killed eight young people at the Six Flags Great Adventure amusement park last week was started by a youth who lit a lighter to find his way, investigators reported today. The investigators said the lighter ignited a large foam-rubber pad in a room that was dark because of a malfunctioning strobe light. The fire, fanned by air-conditioners, then swept through the eight trailers that made up one side of the attraction, the Haunted Castle. The youth who ignited the fire was believed to be 14 years old, and was not believed to be among the victims. The investigating panel reported that the Haunted Castle violated up to a dozen state regulations.

The economy raced ahead at an 8.8 percent annual rate in the first quarter, even faster than previously estimated, the Commerce Department reported today. The new calculation of the gain in the gross national product, the national output of goods and services, compared with earlier estimates of 8.3 percent and 7.2 percent.also said after-tax corporate profits rose in the March quarter after a dip late in 1983. The new figures were regarded as further indications that the 18-month- old recovery, which many economists say is threatened by very high interest rates, will endure well into 1985. But in what is becoming an increasingly frequent response to apparent good news about economic growth, stock prices fell broadly today. Traders said they feared that the continued brisk pace of expansion would keep interest rates high and could lead to an abrupt downturn in the economy.

The unprecedented $7.5 billion emergency aid package extended by Government agencies and private banks to insure the survival of the Continental Illinois National Bank and Trust Company has apparently halted the run on the giant Chicago bank and calmed world financial markets. ''It's been quiet today and the action seemed to stem the outflow,'' a Continental spokesman said yesterday. The spokesman also said the rescue package, the largest such package ever assembled by the Government, was used yesterday by the bank, but he declined to elaborate on the amounts. The package included $2 billion in new capital for the bank and a $5.5 billion line of credit from 28 banks. In addition, the Federal Reserve, the nation's central bank, said it would provide funds to meet daily cash requirements beyond the $7.5 billion commitment.

The Food and Drug Administration today approved the nonprescription sale of a pain reliever that will compete with aspirin and the relatively new drug acetaminophen, which is best known by such brand names as Tylenol and Datril. Both the drug agency and the manufacturers say the newly approved drug, ibuprofen, offers relief from both pain and inflammation, like aspirin, but is less likely to irritate the stomach. They say it presents less risk of harmful overdose than acetaminophen, which does not work against inflammation. And it is described as providing relief for menstrual cramps.

Physicians conducting a full medical examination of President Reagan today discovered and partly removed a small polyp from Mr. Reagan's colon. Hours later they determined that it was benign, the White House said tonight. Larry Speakes, the White House spokesman, said the existence of the polyp was ''a normal development in the intestinal tract'' and caused ''no undue anxiety'' in the President or his aides even before it was diagnosed as benign late in the afternoon. In every other respect, Mr. Speakes asserted, physicians conducting the medical examination of Mr. Reagan at the National Naval Medical Center in Bethesda, Md., reported that he was in good health.