TEL AVIV —  An explosion triggered by a gas leak collapsed a two-story building Monday in Tel Aviv (search), killing at least five people, injuring three and trapping others.

Those killed included two Israeli women, a Nigerian man and woman, and a 5-year-old Filipino girl, police said.

Gidon Baron, an army reserve colonel in charge of rescue efforts, said at least three people were trapped and that chances were good of finding survivors.

Police blamed the blast on a gas leak, but rumors of a Palestinian attack had spread rapidly through a city still jittery despite Sunday's announcement by militants of a temporary halt in attacks on Israelis.

One victim was in her ninth month of pregnancy. Rescue workers tried to save the baby but couldn't dislodge the mother's body from under a large slab of concrete, said rescue services spokesman Moshe Mosco.

"It was her first baby," said Blossom Ani, a neighbor. "I feel very bad about what happened to my friend. I can't talk any more."

The Israeli army brought in electronic equipment, dogs and heavy machinery to help find survivors. Soldiers in yellow hard hats used bulldozers and cranes to move aside rubble. Occasionally turning off the machinery to listen for signs of life, they then dug through the debris with their bare hands.

The building, in a run-down neighborhood of southern Tel Aviv, was home to a mixture of blue-collar Israelis and foreign workers.

Hours after the collapse, a bomb exploded near a travel agency on the other side of town specializing in gambling tours, police said. They said the blast was an attempt to kill reputed organized crime leader Zeb Rosenstein, who was among four people injured.