The bombing took place at 11:03 p.m. local time, as Israeli Prime Minister Ariel Sharon began his talks with President Bush in Washington.
“We know of an explosion in a building…a nightclub in which there was apparently a large number of people,” Chaim Cohen, a police commander told Army radio.
A spokesman with an Israeli ambulance service said part of the three-story building had collapsed. “Some of the wounded are trapped in the building,” he said.
The explosion occurred in the middle of the industrial section of Rishon Letzion, a city with 100,000 residents.
A Lebanese TV station said it received a claim of responsibility from the Palestinian militant group Hamas, but a Hamas spokesman says he cannot confirm that.
Nearly 60 suicide bombings have occurred since the latest spate of Israeli-Palestinian violence flared in September 2000.